## 十、Python编程计算24点（之二）
----From a high school student's view to learnPython
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python 高中生学编程 Python编程入门 计算24点表达式计算 组合问题
三、程序实现
说完了该列举的问题，接下来就是程序的书写部分了，现在我们要回忆之前学的一系列知识，包括函数，列表，循环等等。首先我们来解决组合的书写问题，因为有四个数，我们便可以把这四个数归到同一个列表中，然后再通过调用来运用，但是在这里我们需要创造两个列表，一个是函数里的列表，另一个是函数外引入的参数，因为是要写组合，所以我们就应该将引入的参数分别的赋值给我们在函数内新建的列表，然后再在之后的程序中使用已被赋值的列表。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p></td><td valign="top"><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr/></wbr></span><span>for</span> <span>i1</span> <span>in</span><span>range(</span><span>3</span><span>):</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>0</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>2</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>1</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>2</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>3</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>2</span><span>]</span></p></td></tr></tbody></table>
a就是我们新建的列表，其实列表里的元素随便是什么都可以，只要有四个，因为会被替换掉，接下来就需要用一个循环来解决组合问题。由于有三种情况，所以我们可以用一个三个条件的循环，分别是(ab)(cd) ，(ac) (bd) ，(ad) (bc)
然后再对range函数进行for语句循环操作。这里要注意的一点是：range中是从0开始计算，而且结尾应是前一个数，所以是以3结尾。这样我们就成功的写出了循环的组合语句，我们就不用再在之后的程序中浪费时间重复操作了。
四选三的组合语句也差不多，如下
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p></td><td valign="top"><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr>sign=[</wbr></wbr></span><span><i>'+'</i></span><span>,</span><span><i>'-'</i></span><span>]</span></p><p><span> <wbr> <wbr/></wbr></span><span>for</span> <span>i1</span> <span>in</span><span>range(</span><span>4</span><span>):</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>0</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>2</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>1</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>2</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>2</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>1</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>3</span><span>:a[</span><span>0</span><span>]=c[</span><span>1</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>0</span><span>]</span></p></td></tr></tbody></table>
接下来我们就要进行枚举各种情况了，但是在枚举前，我们应该再思考一下到底有什么地方可以在进行简化。仔细观察前面列的所有情况，我们可以发现含有+-这两个符号的式子很多，有些式子甚至含有两对到三对，但是如果我们一一去列举所有的情况，未免太复杂：+++，++-，+--，+-+，-++，-+-，--+，---一共八种，也就是说我们要为了之一种简单的情况写八遍差不多的代码，那我们为什么不做一个甚至多重的for循环呢？
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p></td><td valign="top"><p><span> <wbr> <wbr>sign=[</wbr></wbr></span><span><i>'+'</i></span><span>,</span><span><i>'-'</i></span><span>]</span></p><p><span> <wbr> <wbr> for</wbr></wbr></span><span>i2</span> <span>in</span> <span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></span><span>for</span> <span>i3</span> <span>in</span><span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span> <span>for</span><span>i4</span> <span>in</span> <span>sign:</span></p></td></tr></tbody></table>
首先建立一个列表（line1）然后再做一个三重循环，当然这里的循环次数和式子中+-的个数要保持一致。但是为什么*/不用for循环来做呢，因为我们发现其实(c*/d)
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><span>16</span></p><p><span>17</span></p></td><td valign="top"><p><span> <wbr> <wbr>num4list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr/></wbr></span><span>for</span> <span>i1</span> <span>in</span><span>range(</span><span>3</span><span>):</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>0</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>2</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>1</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>2</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>3</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>2</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(</wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>')'</i></span><span>)</span></p></td></tr></tbody></table>
看起来很复杂，其实找到规律之后就十分容易了，由于/的符号有顺序一说（a/b和b/a的不同）所以我们需要调换顺序，然后依照规律，我们就可以列出一共10种不同的情况。要注意的是，如果不是str()函数，则需要用双引号来表示字符串的意义。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p></td><td valign="top"><p><span> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>]))</span></p><p><span> <wbr/></span><span> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>]))</span></p></td></tr></tbody></table>
这种情况就是a*/b+-c*/d，由于ab和cd之间都有除号，所以这两个字母都需要调换顺序，而且因为中间的符号有减号，所以我们还需要将前两个数字和后两个数字调换顺序来满足所有的情况。而由于只里面只有一个+-所以并不需要用循环来简化，只需枚举即可。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><span>16</span></p></td><td valign="top"><p><span> <wbr> <wbr>num3list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>sign=[</wbr></wbr></span><span><i>'+'</i></span><span>,</span><span><i>'-'</i></span><span>]</span></p><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr/></wbr></span><span>for</span> <span>i1</span> <span>in</span><span>range(</span><span>3</span><span>):</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>0</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>2</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>1</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>2</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>3</span><span>];a[</span><span>2</span><span>]=c[</span><span>1</span><span>];a[</span><span>3</span><span>]=c[</span><span>2</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>for</span> <span>i2</span><span>in</span> <span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></span><span>for</span> <span>i3</span> <span>in</span><span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span> <span>for</span><span>i4</span> <span>in</span> <span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span> <span>if</span><span>i2==</span><span><i>'+'</i></span><span>:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>i2=</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>''</i></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num3list.append(i2+</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+i3+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+i4+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num3list.append(i2+</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+i3+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+i4+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>)</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num3list.append(i2+</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+str(a[</span><span>2</span><span>])+i3+str(a[</span><span>3</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+</span><span><i>'('</i></span><span>+str(a[</span><span>0</span><span>])+i4+str(a[</span><span>1</span><span>])+</span><span><i>')'</i></span><span>)</span></p></td></tr></tbody></table>
这是(a+-b)*/(c+-d)的情况，要注意的是，在这几行代码中我们用到了一个三重循环，而+-只有两种，原因是我们在括号的最前面又加了一个符号，仔细观察，我们可以发现这个符号是对第一个括号内的正负进行的判定，因为在第一个括号内会出现a与b调换的情况，而且我们发现第一个括号内会出现答案是负数的情况，但是不要忘了，在第二个括号内的情况和第一个括号内的情况是完全相同的，所以第二个括号内也会出现负数的情况，当第一和第二个括号内的结果均为负数时，就又变成了正数（中间是*/），所以我们并不用在每个括号前加一个符号，取而代之的是在整个式子之前加正负号就可以了。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><span>16</span></p><p><span>17</span></p></td><td valign="top"><p><span> <wbr> <wbr>num4list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[99,99,99,99]</wbr></wbr></span></p><p><span> <wbr> <wbr> for i1 inrange(3):</wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==0:a[0]=c[0];a[1]=c[1];a[2]=c[2];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==1:a[0]=c[0];a[1]=c[2];a[2]=c[1];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==2:a[0]=c[0];a[1]=c[3];a[2]=c[1];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[0])+'*'+str(a[1])+')'+'/'+'('+str(a[2])+'*'+str(a[3])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[2])+'*'+str(a[3])+')'+'/'+'('+str(a[0])+'*'+str(a[1])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[2])+'*'+str(a[3])+')'+'/'+'('+str(a[0])+'/'+str(a[1])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[2])+'*'+str(a[3])+')'+'/'+'('+str(a[1])+'/'+str(a[0])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[0])+'*'+str(a[1])+')'+'/'+'('+str(a[2])+'/'+str(a[3])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[0])+'*'+str(a[1])+')'+'/'+'('+str(a[3])+'/'+str(a[2])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[0])+'*'+str(a[1])+')'+'*'+'('+str(a[2])+'/'+str(a[3])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[0])+'*'+str(a[1])+')'+'*'+'('+str(a[3])+'/'+str(a[2])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[2])+'*'+str(a[3])+')'+'*'+'('+str(a[0])+'/'+str(a[1])+')')</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append('('+str(a[2])+'*'+str(a[3])+')'+'*'+'('+str(a[1])+'/'+str(a[0])+')')</wbr></wbr></wbr></wbr></span></p></td></tr></tbody></table>
这是(a*/b)*/(c*/d)的情况，大家如果观察可以发现第一个括号内并没有/的情况，这是因为如果第一个括号内的符号是/，两个括号中间的符号必须是*，否则答案不可能是24，但是如果中间的符号是*，就没必要考虑两个括号的摆放顺序的问题了，所以我索性让第一个括号的符号均为*，看起来也比较整齐。其它的步骤还是和前几个差不多，调换/两端元素的位置，找到规律之后十分简单。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p></td><td valign="top"><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'+'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>0</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr>num4list.append(str(a[</wbr></wbr></wbr></wbr></span><span>2</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'-'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>]))</span></p></td></tr></tbody></table>
这种情况就是a*/b+-c*/d，由于也是两个数字一组的情况，之前的组合代码和上一种情况相同，所以我就索性将两种情况合并在一起，节省了很多时间，但是要注意的是这种情况包含两个*/和一个+-，所以情况比较多，但是/-/的情况显然不可能所以排除，大家要注意不要遗漏或者重复。
接下来就是三个一组的情况：
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><br/></p></td><td valign="top"><p><span> <wbr> <wbr>num5list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr>sign=[</wbr></wbr></span><span><i>'+'</i></span><span>,</span><span><i>'-'</i></span><span>]</span></p><p><span> <wbr> <wbr/></wbr></span><span>for</span> <span>i1</span> <span>in</span><span>range(</span><span>4</span><span>):</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>0</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>2</span><span>];a[</span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>1</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>1</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>2</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>2</span><span>:a[</span><span>0</span><span>]=c[</span><span>0</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>1</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>if</span><span>i1==</span><span>3</span><span>:a[</span><span>0</span><span>]=c[</span><span>1</span><span>];a[</span><span>1</span><span>]=c[</span><span>2</span><span>];a[</span><span>2</span><span>]=c[</span><span>3</span><span>];a[</span><span>3</span><span>]=c[</span><span>0</span><span>]</span></p><p><span> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></span> <span>for</span> <span>i2</span><span>in</span> <span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></span><span>for</span> <span>i3</span> <span>in</span><span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span> <span>for</span><span>i4</span> <span>in</span> <span>sign:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr/></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span> <span>if</span><span>i2==</span><span><i>'+'</i></span><span>:</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>i2=</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>''</i></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num5list.append(</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+i2+str(a[</span><span>0</span><span>])+i3+str(a[</span><span>1</span><span>])+i4+str(a[</span><span>2</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num5list.append(</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span><span><i>'('</i></span><span>+i2+str(a[</span><span>0</span><span>])+i3+str(a[</span><span>1</span><span>])+i4+str(a[</span><span>2</span><span>])+</span><span><i>')'</i></span><span>+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p></td></tr></tbody></table>
(a+-b+-c)*/d由于是三个一组的情况，之前在组合问题中说过有四种情况，而且由于前两个符号都是+-，而我又在第一个数字前加了一个符号来避免调换顺序，我们可以用一个三重循环来解决重复书写的问题，和之前介绍过的技巧一样。同样大家也要注意第一个符号是+的情况是无意义的，所以要把它去掉（line12-line13）。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><span>16</span></p><p><span>17</span></p><p><span>18</span></p><p><span>19</span></p><p><span>20</span></p><p><span>21</span></p><p><span>22</span></p><p><span>23</span></p><p><span>24</span></p><p><span>25</span></p><p><span>26</span></p><p><span>27</span></p><p><span>28</span></p><p><span>29</span></p><p><span>30</span></p><p><span>31</span></p><p><span>32</span></p><p><span>33</span></p><p><span>34</span></p><p><span>35</span></p><p><span>36</span></p><p><span>37</span></p><p><span>38</span></p><p><span>39</span></p><p><span>40</span></p><p><span>41</span></p><p><span>42</span></p><p><span>43</span></p><p><span>44</span></p></td><td valign="top"><p><span> <wbr> <wbr>num6list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[99,99,99,99]</wbr></wbr></span></p><p><span> <wbr> <wbr>sign=['+','-']</wbr></wbr></span></p><p><span> <wbr> <wbr> for i1 inrange(4):</wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==0: a[0]=c[0]; a[1]=c[1]; a[2]=c[2];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==1: a[0]=c[0]; a[1]=c[1]; a[2]=c[3];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==2: a[0]=c[0]; a[1]=c[2]; a[2]=c[3];a[3]=c[1]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==3: a[0]=c[1]; a[1]=c[2]; a[2]=c[3];a[3]=c[0]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> for i2 in sign:</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(str(a[0])+'*'+str(a[1])+'*'+str(a[2])+i2+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(str(a[0])+'*'+str(a[1])+'/'+str(a[2])+i2+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(str(a[0])+'*'+str(a[2])+'/'+str(a[1])+i2+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(str(a[2])+'*'+str(a[1])+'/'+str(a[0])+i2+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> for i3 insign:</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i2=='-' and i3=='-':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>continue</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i3=='+':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>i3=''</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[1])+'*'+str(a[2])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[1])+'/'+str(a[2])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[2])+'/'+str(a[1])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[1])+'*'+str(a[2])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[1])+'/'+str(a[2])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[0])+i2+str(a[2])+'/'+str(a[1])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[0])+'*'+str(a[2])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[0])+'/'+str(a[2])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[2])+'/'+str(a[0])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[0])+'*'+str(a[2])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[0])+'/'+str(a[2])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[1])+i2+str(a[2])+'/'+str(a[0])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[1])+'*'+str(a[0])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[1])+'/'+str(a[0])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[0])+'/'+str(a[1])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[1])+'*'+str(a[0])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[1])+'/'+str(a[0])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append('('+i3+str(a[2])+i2+str(a[0])+'/'+str(a[1])+')'+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[0])+i2+str(a[1])+'*'+str(a[2])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[0])+i2+str(a[2])+'/'+str(a[1])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[0])+i2+str(a[1])+'/'+str(a[2])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[1])+i2+str(a[0])+'*'+str(a[2])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[1])+i2+str(a[0])+'/'+str(a[2])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[1])+i2+str(a[2])+'/'+str(a[0])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[2])+i2+str(a[1])+'*'+str(a[0])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[2])+i2+str(a[1])+'/'+str(a[0])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num6list.append(i3+str(a[3])+'/'+'('+str(a[2])+i2+str(a[0])+'/'+str(a[1])+')')</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p></td></tr></tbody></table>
接下来这个是a*/b*/c+-d和(a+-b*/c)*/d的两种情况的合并，由于这两种都是三个一组的情况，合并可以少些很多重复的代码，但是要注意的是，这两种情况并不是在最后合并，它们各自的前提条件的代码有所区别。因为第一个式子中只有一个+-，而第二个式子中有两个（式子最前要加一个符号），所以所进行的循环操作的次数是不一样的，但是我们仍然可以把它们合并在一起，只需在第一个循环操作结束后直接输出第一个式子的结果，把它们加入到列表中，然后再进行下两个循环操作就可以了。但是对于第二个式子，我们要注意的是在括号之后的符号有/，所以就不可避免的要调换位置，但是再调换位置之后会出现代码不整齐的情况，影响美观，所以我们不妨把这一类单分出来放在最下面。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p></td><td valign="top"><p><span> <wbr> <wbr>num7list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[</wbr></wbr></span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>,</span><span>99</span><span>]</span></p><p><span> <wbr> <wbr>a[</wbr></wbr></span><span>0</span><span>]=c[</span><span>0</span><span>]</span></p><p><span> <wbr> <wbr>a[</wbr></wbr></span><span>1</span><span>]=c[</span><span>1</span><span>]</span></p><p><span> <wbr> <wbr>a[</wbr></wbr></span><span>2</span><span>]=c[</span><span>2</span><span>]</span></p><p><span> <wbr> <wbr>a[</wbr></wbr></span><span>3</span><span>]=c[</span><span>3</span><span>]</span></p><p><span> <wbr> <wbr>num7list.append(str(a[</wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>3</span><span>]))</span></p><p><span> <wbr> <wbr>num7list.append(str(a[</wbr></wbr></span><span>3</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>0</span><span>]))</span></p><p><span> <wbr> <wbr>num7list.append(str(a[</wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>2</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>1</span><span>]))</span></p><p><span> <wbr> <wbr>num7list.append(str(a[</wbr></wbr></span><span>0</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>1</span><span>])+</span><span><i>'*'</i></span><span>+str(a[</span><span>3</span><span>])+</span><span><i>'/'</i></span><span>+str(a[</span><span>2</span><span>]))</span></p></td></tr></tbody></table>
这种就是a*/b*/c*/d的情况，但是由于一乘两除或者三个除号的情况是不可能形成24的，所以我们这里只考虑两乘一除的情况，由于没有+-，我们就不需要组合的代码，只需将c列表中的元素赋值给a列表中的每个元素即可。
<table cellspacing="0" cellpadding="0"><tbody><tr><td valign="top"><p><span>1</span></p><p><span>2</span></p><p><span>3</span></p><p><span>4</span></p><p><span>5</span></p><p><span>6</span></p><p><span>7</span></p><p><span>8</span></p><p><span>9</span></p><p><span>10</span></p><p><span>11</span></p><p><span>12</span></p><p><span>13</span></p><p><span>14</span></p><p><span>15</span></p><p><span>16</span></p><p><span>17</span></p><p><span>18</span></p><p><span>19</span></p><p><span>20</span></p><p><span>21</span></p><p><span>22</span></p><p><span>23</span></p><p><span>24</span></p><p><span>25</span></p><p><span>26</span></p><p><span>27</span></p><p><span>28</span></p><p><span>29</span></p><p><span>30</span></p><p><span>31</span></p><p><span>32</span></p><p><span>33</span></p><p><span>34</span></p><p><span>35</span></p><p><span>36</span></p><p><span>37</span></p><p><span>38</span></p><p><span>39</span></p><p><span>40</span></p><p><span>41</span></p><p><span>42</span></p><p><span>43</span></p><p><span>44</span></p><p><span>45</span></p><p><span>46</span></p><p><span>47</span></p></td><td valign="top"><p><span> <wbr> <wbr>num8list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[99,99,99,99]</wbr></wbr></span></p><p><span> <wbr> <wbr>sign=['+','-']</wbr></wbr></span></p><p><span> <wbr> <wbr> for i1 inrange(6):</wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==0:a[0]=c[0];a[1]=c[1];a[2]=c[2];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==1:a[0]=c[0];a[1]=c[2];a[2]=c[1];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==2:a[0]=c[0];a[1]=c[3];a[2]=c[1];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==3:a[0]=c[2];a[1]=c[3];a[2]=c[0];a[3]=c[1]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==4:a[0]=c[1];a[1]=c[3];a[2]=c[0];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==5:a[0]=c[1];a[1]=c[2];a[2]=c[0];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> for i2 in sign:</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> for i3 insign:</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i2=='-' andi3=='-':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> continue</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i2=='+':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> i2=''</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[2])+'+'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[3])+'+'+str(a[2]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[2])+'-'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[3])+'-'+str(a[2]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'/'+str(a[2])+'+'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'/'+str(a[3])+'+'+str(a[2]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'/'+str(a[2])+'-'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num8list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'/'+str(a[3])+'-'+str(a[2]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><br/></p><p><span> <wbr> <wbr>num10list=[]</wbr></wbr></span></p><p><span> <wbr> <wbr>a=[99,99,99,99]</wbr></wbr></span></p><p><span> <wbr> <wbr>sign=['+','-']</wbr></wbr></span></p><p><span> <wbr> <wbr> for i1 inrange(6):</wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==0:a[0]=c[0];a[1]=c[1];a[2]=c[2];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==1:a[0]=c[0];a[1]=c[2];a[2]=c[1];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==2:a[0]=c[0];a[1]=c[3];a[2]=c[1];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==3:a[0]=c[2];a[1]=c[3];a[2]=c[0];a[3]=c[1]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==4:a[0]=c[1];a[1]=c[3];a[2]=c[0];a[3]=c[2]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> if i1==5:a[0]=c[1];a[1]=c[2];a[2]=c[0];a[3]=c[3]</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> for i2 in sign:</wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> for i3 insign:</wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i2=='-' andi3=='-':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> continue</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if i2=='+':</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> i2=''</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num10list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[2])+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num10list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'/'+str(a[2])+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num10list.append('('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[2])+'/'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num10list.append(str(a[2])+'/'+'('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[3]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><span> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>num10list.append(str(a[3])+'/'+'('+i2+str(a[0])+i3+str(a[1])+')'+'*'+str(a[2]))</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p><p><br/></p></td></tr></tbody></table>
接下来的这两种情况就是最复杂的组合情况了，(a+-b)*/c+-d和(a+-b)*/c*/d这两种情况下的组合，由于这两种情况下用六种的组合情况可以少写一些代码，并且更加简单，我们不妨把三种的组合代码改为六种。
到此为止，我们就把所有的组合的情况都列了出来，但是还有一些后续的程序来保证程序的运行和美观。第一就是我们应该把每一种情况的代码都写入到一个函数中，这样如果我们以后要用到的话，直接调用函数就能解决问题，第二就是我们还应该把所有的情况都加在一起，因为验证的时候要用到的是所有的情况，而把它们合并到一个大函数中就不用一个一个调用了。
四、如何利用之前的函数来进行计算
由于我们的程序越做越大，如果我们还把所有的函数，代码都放在一个模块中，显然是十分的复杂以及不方便，这时我们就要把代码写入不同的文件中，但是最后运行的时候，每个文件都需要被运行，那们我们怎么达成呢？这时我们就要用到import语句了，import语句的主要作用就是将多个文件引入到一个文件中，从而在运行一个文件时，其他的文件也能够被运行。
import语句的语法：
import 语句的模块顺序 我们推荐所有的模块在 Python 模块的开头部分导入。而且好按照这样的顺序:
Python 标准库模块
Python 第三方模块
应用程序自定义模块
然后使用一个空行分割这三类模块的导入语句。 这将确保模块使用固定的习惯导入, 有助于减 少每个模块需要的import 语句数目。 其他的提示请参考《 Python 风格指南》（Python’s Style Guide）,PEP8
fromtransitionimport*
fromexcercise4importbiglist
fromdisorderimportchange_order
fromexcercise1importcirculate
这就是我用到的几个import语句。
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