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.

Explanation : Idea behind interchanging diagonals of a 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<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; 
} 

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 

Python3

# Python program to interchange  
# the diagonals of matrix 
N = 3; 
  
# Function to interchange diagonals 
def interchangeDiagonals(array): 
  
    # swap elements of diagonal 
    for i in range(N): 
        if (i != N / 2): 
            temp = array[i][i]; 
            array[i][i] = array[i][N - i - 1]; 
            array[i][N - i - 1] = temp; 
          
    for i in range(N): 
        for j in range(N): 
            print(array[i][j], end = " "); 
        print(); 
  
# Driver Code 
if __name__ == '__main__': 
    array = [ 4, 5, 6 ],[ 1, 2, 3 ],[ 7, 8, 9 ]; 
    interchangeDiagonals(array); 
      
# This code is contributed by Rajput-Ji 

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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My Personal Notes

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

C

Java

Python3

C#

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