Program to Interchange Diagonals of Matrix

Given a square matrix of order n*n, you have to interchange the elements of both diagonals.

Examples :

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}

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Expalnation : Idea behind interchanging diagonals of square matrix is simple. Iterate from 0 to n-1 and for each iteration you have to swap a[i][i] and a[i][n-i-1]. Time complexity : O(n)

C

 // C program to interchange  // the diagonals of matrix #include 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; }

Java

 // Java program to interchange  // the diagonals of matrix import java.io.*;    class GFG  {     public static int N = 3;            // Function to interchange diagonals     static void interchangeDiagonals(int array[][])     {         // swap elements of diagonal         for (int i = 0; i < N; ++i)             if (i != N / 2)             {                 int temp = array[i][i];                 array[i][i] = array[i][N - i - 1];                 array[i][N - i - 1] = temp;             }            for (int i = 0; i < N; ++i)         {             for (int j = 0; j < N; ++j)                 System.out.print(array[i][j]+" ");             System.out.println();         }     }            // Driver Code     public static void main (String[] args)      {         int array[][] = { {4, 5, 6},                         {1, 2, 3},                         {7, 8, 9}                         };         interchangeDiagonals(array);     } }    // This code is contributed by Pramod Kumar

C#

 // C# program to interchange  // the diagonals of matrix using System;    class GFG  {     public static int N = 3;            // Function to interchange diagonals     static void interchangeDiagonals(int [,]array)     {         // swap elements of diagonal         for (int i = 0; i < N; ++i)             if (i != N / 2)             {                 int temp = array[i, i];                 array[i, i] = array[i, N - i - 1];                 array[i, N - i - 1] = temp;             }            for (int i = 0; i < N; ++i)         {             for (int j = 0; j < N; ++j)                 Console.Write(array[i, j]+" ");             Console.WriteLine();         }     }            // Driver Code     public static void Main ()      {         int [,]array = { {4, 5, 6},                         {1, 2, 3},                         {7, 8, 9}                         };         interchangeDiagonals(array);     } }    // This code is contributed by vt_m.

Output:

6 5 4
1 2 3
9 8 7

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Improved By : vt_m

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