程序打印数组的下三角和上三角矩阵 · GeeksForGeeks 中文系列教程

# 程序打印数组的下三角和上三角矩阵 > 原文： [https://www.geeksforgeeks.org/program-print-lower-triangular-upper-triangular-matrix-array/](https://www.geeksforgeeks.org/program-print-lower-triangular-upper-triangular-matrix-array/) 先决条件– [C/C++ 中的多维数组](https://www.geeksforgeeks.org/multidimensional-arrays-c-cpp/) 给定一个二维数组，编写一个程序以打印下三角矩阵和上三角矩阵。 * 下三角矩阵是一个矩阵，其中包含在原理对角线以下的元素（包括原理对角线元素），其余元素为 0。 * 上三角矩阵是一个矩阵，其中包含在原则对角线上的元素（包括原则对角元素），其余元素为 0。 **下三角**： ![{\displaystyle \begin{bmatrix} A_{00} & 0 & 0 & ... & 0\\ A_{10} & A_{11} & 0 & ... & 0\\ A_{20} & A_{21} & A_{22} & ... & 0\\ . & . & . & . & .\\ . & & & & \\ . & & & & \\ . & & & & \\ . & & & & \\ . & & & & \\ A_{row0} & A_{row1} & A_{row2} & ... & A_{rowcol} \end{bmatrix}}](https://img.kancloud.cn/b3/47/b3471785243620f8950804e21f70876f_416x319.png "Rendered by QuickLaTeX.com") **上矩形**： ![{\displaystyle \begin{bmatrix} A_{00} & A_{01} & A_{02} & ... & A_{0col}\\ 0 & A_{11} & A_{22} & ... & A_{1col}\\ 0 & 0 & A_{22} & ... & A_{2col}\\ . & . & . & . & .\\ . & & & & \\ . & & & & \\ . & & & & \\ . & & & & \\ . & & & & \\ 0 & 0 & 0 & ... & A_{rowcol} \end{bmatrix}}](https://img.kancloud.cn/67/48/6748227b69b8c57e692e39498959d288_342x319.png "Rendered by QuickLaTeX.com") **示例**： ``` Input : matrix[3][3] = {1 2 3 4 5 6 7 8 9} Output : Lower : 1 0 0 Upper : 1 2 3 4 5 0 0 5 6 7 8 9 0 0 9 Input : matrix[3][3] = {7 8 9 3 2 1 6 5 4} Output : Lower : 7 0 0 Upper : 7 8 9 3 2 0 0 2 1 6 5 4 0 0 4 ``` **步骤**： 1. 对于下三角矩阵，我们分别检查索引位置 i 和 j，即行和列。如果列位置大于行位置，我们只需将该位置设为 0。 2. 对于上三角矩阵，我们分别检查索引位置 i 和 j，即行和列。如果列位置小于行位置，我们只需将该位置设为 0。 ## C++ ```cpp // C++ program to print Lower // triangular and Upper triangular // matrix of an array #include<iostream> using namespace std; // Function to form // lower triangular matrix void lower(int matrix[3][3], int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i < j) { cout << "0" << " "; } else cout << matrix[i][j] << " "; } cout << endl; } } // Function to form upper triangular marix void upper(int matrix[3][3], int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i > j) { cout << "0" << " "; } else cout << matrix[i][j] << " "; } cout << endl; } } // Driver Code int main() { int matrix[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; int row = 3, col = 3; cout << "Lower triangular matrix: \n"; lower(matrix, row, col); cout << "Upper triangular matrix: \n"; upper(matrix, row, col); return 0; } ``` ## Java ```java // Java program to print Lower // triangular and Upper triangular // matrix of an array class GFG { // method to form lower // triangular matrix static void lower(int matrix[][], int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i < j) { System.out.print("0" + " "); } else System.out.print(matrix[i][j] + " "); } System.out.println(); } } // Method to form upper // triangular matrix static void upper(int matrix[][], int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i > j) { System.out.print("0" + " "); } else System.out.print(matrix[i][j] + " "); } System.out.println(); } } // Driver Code public static void main(String args[]) { int matrix[][] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; int row = 3, col = 3; System.out.println("Lower triangular matrix: "); lower(matrix, row, col); System.out.println("Upper triangular matrix: "); upper(matrix, row, col); } } ``` ## Python3 ```py # Python3 program to print Lower # triangular and Upper triangular # matrix of an array # Function to form lower triangular # matrix def lower(matrix, row, col): for i in range(0, row): for j in range(0, col): if (i < j): print("0", end = " "); else: print(matrix[i][j], end = " " ); print(" "); # Function to form upper triangular marix def upper(matrix, row, col): for i in range(0, row): for j in range(0, col): if (i > j): print("0", end = " "); else: print(matrix[i][j], end = " " ); print(" "); # Driver Code matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]; row = 3; col = 3; print("Lower triangular matrix: "); lower(matrix, row, col); print("Upper triangular matrix: "); upper(matrix, row, col); # This code is contributed by # Shivi_Aggarwal ``` ## C# ```cs // C# program to print // Lower triangular and // Upper triangular // matrix of an array using System; class GFG { // method to form lower // triangular matrix static void lower(int [,]matrix, int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i < j) { Console.Write("0" + " "); } else Console.Write(matrix[i, j] + " "); } Console.WriteLine(); } } // Method to form upper // triangular matrix static void upper(int [,]matrix, int row, int col) { int i, j; for (i = 0; i < row; i++) { for (j = 0; j < col; j++) { if (i > j) { Console.Write("0" + " "); } else Console.Write(matrix[i, j] + " "); } Console.WriteLine(); } } // Driver Code static public void Main () { int [,]matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; int row = 3, col = 3; Console.WriteLine("Lower triangular matrix: "); lower(matrix, row, col); Console.WriteLine("Upper triangular matrix: "); upper(matrix, row, col); } } // This code is contributed by ajit ``` ## PHP ```php <?php // PHP program to print Lower // triangular and Upper triangular // matrix of an array // Function to form // lower triangular matrix function lower($matrix, $row, $col) { $i; $j; for ($i = 0; $i < $row; $i++) { for ($j = 0; $j < $col; $j++) { if ($i < $j) { echo "0" , " "; } else echo $matrix[$i][$j] , " "; } echo "\n"; } } // Function to form // upper triangular marix function upper($matrix, $row, $col) { $i; $j; for ($i = 0; $i < $row; $i++) { for ($j = 0; $j < $col; $j++) { if ($i > $j) { echo "0" , " "; } else echo $matrix[$i][$j] ," "; } echo "\n"; } } // Driver Code $matrix = array (array (1, 2, 3), array (4, 5, 6), array (7, 8, 9)); $row = 3; $col = 3; echo "Lower triangular matrix: \n"; lower($matrix, $row, $col); echo "Upper triangular matrix: \n"; upper($matrix, $row, $col); // This code is contributed by jit_t ?> ``` **输出**： ``` Lower triangular matrix: 1 0 0 4 5 0 7 8 9 Upper triangular matrix: 1 2 3 0 5 6 0 0 9 ```