# 矩陣對角線互換程序 > 原文： [https://www.geeksforgeeks.org/program-to-interchange-diagonals-of-matrix/](https://www.geeksforgeeks.org/program-to-interchange-diagonals-of-matrix/) 給定 n * n 階方陣，您必須交換兩個對角線的元素。 **示例**： ``` Input : matrix[][] = {1, 2, 3, 4, 5, 6, 7, 8, 9} Output : matrix[][] = {3, 2, 1, 4, 5, 6, 9, 8, 7} Input : matrix[][] = {4, 2, 3, 1, 5, 7, 6, 8, 9, 11, 10, 12, 16, 14, 15, 13} Output : matrix[][] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 11, 14, 15, 16} ``` **解釋**：交換方陣對角線背后的想法很簡單。 從 0 迭代到 n-1，對于每次迭代，您都必須交換 a [i] [i]和 a [i] [n-i-1]。  時間復雜度：`O(n)` ## C ``` // C program to interchange? // the diagonals of matrix #include<bits/stdc++.h> using namespace std; #define N 3 // Function to interchange diagonals void interchangeDiagonals(int array[][N]) { ????// swap elements of diagonal ????for (int i = 0; i < N; ++i) ????if (i != N / 2) ????swap(array[i][i], array[i][N - i - 1]); ????for (int i = 0; i < N; ++i) ????{ ????for (int j = 0; j < N; ++j) ????????????printf(" %d", array[i][j]); ????printf("\n"); ????} } // Driver Code int main() { ????int array[N][N] = {4, 5, 6, ????????????????????1, 2, 3, ????????????????????7, 8, 9}; ????interchangeDiagonals(array); ????return 0; } ```