**一. 题目描述**
Given an array of non-negative integers, you are initially positioned at the first index of the array.
Each element in the array represents your maximum jump length at that position.
Determine if you are able to reach the last index.
For example:
`A = [2,3,1,1,4]`, return true.
`A = [3,2,1,0,4]`, return false.
**二. 题目分析**
该题的大意是,给定一个数组,从第一个元素开始,元素的值表示能够往后跳的最大距离,问按照这种规则,该数组是否能跳到最后一个元素。
解题的基本思路是贪心算法。当然,使用动态规划也是完全可以解决的,也贴出网上一种动规代码。
**三. 示例代码**
~~~
// greedy algorithm
class Solution {
public:
bool canJump(int A[], int n) {
if(n == 0 || n == 1){
return true;
}
int maxStep = A[0];
for(int index = 1 ; index < n ; ++index)
{
if(maxStep == 0) return false;
--maxStep;
if(maxStep < A[index])
maxStep = A[index];
if(maxStep + index >= n - 1) // 满足条件
return true;
}
}
};
~~~
~~~
// DP algorithm
class Solution {
public:
bool canJump(int A[], int n)
{
vector<int> f(n, 0);
f[0] = 0;
for (int i = 1; i < n; i++)
{
f[i] = max(f[i - 1], A[i - 1]) - 1;
if (f[i] < 0) return false;
}
return f[n - 1] >= 0;
}
};
~~~
**四. 小结**
该题的思路是,使maxStep一直保持最大的能移动步数。
- 前言
- 2Sum
- 3Sum
- 4Sum
- 3Sum Closest
- Remove Duplicates from Sorted Array
- Remove Duplicates from Sorted Array II
- Search in Rotated Sorted Array
- Remove Element
- Merge Sorted Array
- Add Binary
- Valid Palindrome
- Permutation Sequence
- Single Number
- Single Number II
- Gray Code(2016腾讯软件开发笔试题)
- Valid Sudoku
- Rotate Image
- Power of two
- Plus One
- Gas Station
- Set Matrix Zeroes
- Count and Say
- Climbing Stairs(斐波那契数列问题)
- Remove Nth Node From End of List
- Linked List Cycle
- Linked List Cycle 2
- Integer to Roman
- Roman to Integer
- Valid Parentheses
- Reorder List
- Path Sum
- Simplify Path
- Trapping Rain Water
- Path Sum II
- Factorial Trailing Zeroes
- Sudoku Solver
- Isomorphic Strings
- String to Integer (atoi)
- Largest Rectangle in Histogram
- Binary Tree Preorder Traversal
- Evaluate Reverse Polish Notation(逆波兰式的计算)
- Maximum Depth of Binary Tree
- Minimum Depth of Binary Tree
- Longest Common Prefix
- Recover Binary Search Tree
- Binary Tree Level Order Traversal
- Binary Tree Level Order Traversal II
- Binary Tree Zigzag Level Order Traversal
- Sum Root to Leaf Numbers
- Anagrams
- Unique Paths
- Unique Paths II
- Triangle
- Maximum Subarray(最大子串和问题)
- House Robber
- House Robber II
- Happy Number
- Interlaving String
- Minimum Path Sum
- Edit Distance
- Best Time to Buy and Sell Stock
- Best Time to Buy and Sell Stock II
- Best Time to Buy and Sell Stock III
- Best Time to Buy and Sell Stock IV
- Decode Ways
- N-Queens
- N-Queens II
- Restore IP Addresses
- Combination Sum
- Combination Sum II
- Combination Sum III
- Construct Binary Tree from Inorder and Postorder Traversal
- Construct Binary Tree from Preorder and Inorder Traversal
- Longest Consecutive Sequence
- Word Search
- Word Search II
- Word Ladder
- Spiral Matrix
- Jump Game
- Jump Game II
- Longest Substring Without Repeating Characters
- First Missing Positive
- Sort Colors
- Search for a Range
- First Bad Version
- Search Insert Position
- Wildcard Matching