# 程序检查矩阵是否为上三角 > 原文： [https://www.geeksforgeeks.org/program-check-matrix-upper-triangular/](https://www.geeksforgeeks.org/program-check-matrix-upper-triangular/) 给定一个正方形矩阵，任务是检查矩阵是否为上三角形式。 如果主对角线以下的所有条目均为零，则方阵称为上三角。  例子： ``` Input : mat[4][4] = {{1, 3, 5, 3}, {0, 4, 6, 2}, {0, 0, 2, 5}, {0, 0, 0, 6}}; Output : Matrix is in Upper Triangular form. Input : mat[4][4] = {{5, 6, 3, 6}, {0, 4, 6, 6}, {1, 0, 8, 5}, {0, 1, 0, 6}}; Output : Matrix is not in Upper Triangular form. ``` ## C++ ```cpp // Program to check upper triangular matrix. #include <bits/stdc++.h> #define N 4 using namespace std; // Function to check matrix is in upper triangular // form or not. bool isUpperTriangularMatrix(int mat[N][N]) {     for (int i = 1; i < N; i++)         for (int j = 0; j < i; j++)             if (mat[i][j] != 0)                 return false;     return true; } // Driver function. int main() {     int mat[N][N] = { { 1, 3, 5, 3 },                       { 0, 4, 6, 2 },                       { 0, 0, 2, 5 },                       { 0, 0, 0, 6 } };     if (isUpperTriangularMatrix(mat))         cout << "Yes";     else         cout << "No";     return 0; } ``` ## Java ```java // Java Program to check upper  // triangular matrix. import java.util.*; import java.lang.*; public class GfG {     private static final int N = 4;     // Function to check matrix is in     // upper triangular form or not.     public static Boolean isUpperTriangularMatrix(int mat[][])     {         for (int i = 1; i < N ; i++)             for (int j = 0; j < i; j++)                 if (mat[i][j] != 0)                     return false;         return true;     }      // driver function     public static void main(String argc[]){         int[][] mat= { { 1, 3, 5, 3 },                        { 0, 4, 6, 2 },                        { 0, 0, 2, 5 },                        { 0, 0, 0, 6 } };         if (isUpperTriangularMatrix(mat))             System.out.println("Yes");         else             System.out.println("No");     } } /* This code is contributed by Sagar Shukla */ ``` ## Python3 ```py # Python3 Program to check upper  # triangular matrix. # Function to check matrix  # is in upper triangular def isuppertriangular(M):     for i in range(1, len(M)):         for j in range(0, i):             if(M[i][j] != 0):                      return False     return True # Driver function. M = [[1,3,5,3],     [0,4,6,2],     [0,0,2,5],     [0,0,0,6]] if isuppertriangular(M):     print ("Yes") else:     print ("No") # This code is contributed by Anurag Rawat ``` ## C# ```cs // C# Program to check upper  // triangular matrix. using System; public class GfG {     private static int N = 4;     // Function to check matrix is in     // upper triangular form or not.     public static bool isUpperTriangularMatrix(int [,]mat)     {         for (int i = 1; i < N ; i++)             for (int j = 0; j < i; j++)                 if (mat[i, j] != 0)                     return false;         return true;     }      // Driver function     public static void Main(){         int [,]mat= { { 1, 3, 5, 3 },                     { 0, 4, 6, 2 },                     { 0, 0, 2, 5 },                     { 0, 0, 0, 6 } };         if (isUpperTriangularMatrix(mat))             Console.WriteLine("Yes");         else             Console.WriteLine("No");     } } /* This code is contributed by vt_m */ ``` ## PHP ```php <?php // PHP Program to check upper  // triangular matrix. $N = 4; // Function to check matrix is  // in upper triangular form or // not. function isUpperTriangularMatrix($mat) {     global $N;     for ($i = 1; $i < $N; $i++)         for ($j = 0; $j < $i; $j++)             if ($mat[$i][$j] != 0)                 return false;     return true; }     // Driver Code     $mat = array(array(1, 3, 5, 3),                  array(0, 4, 6, 2) ,                  array(0, 0, 2, 5),                  array(0, 0, 0, 6));     if (isUpperTriangularMatrix($mat))         echo "Yes";     else         echo"No"; // This code is contributed by anuj_67\. ?> ``` Output: ``` Yes ``` * * * * * *