Interchange elements of first and last rows in matrix

Given a 4 x 4 matrix, we have to interchange the elements of first and last row and show the resulting matrix.

Examples :

Input : 3 4 5 0
        2 6 1 2
        2 7 1 2
        2 1 1 2
Output : 2 1 1 2
         2 7 1 2
         2 6 1 2
         3 4 5 0

Input : 9 7 5 1
        2 3 4 1
        5 6 6 5
        1 2 3 1
Output : 1 2 3 1
         2 3 4 1
         5 6 6 5
         9 7 5 1

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

The approach is very simple, we can simply swap the elements of first and last row of the matrix inorder to get the desired matrix as output.

Below is the implementation of the approach :

C++

// C++ code to swap the element of first 
// and last row and display the result 
#include <iostream> 
using namespace std; 
  
#define n 4 
  
void interchangeFirstLast(int m[][n]) 
{ 
        int rows = n; 
          
        // swapping of element between first 
        // and last rows 
        for (int i = 0; i < n; i++) 
        { 
            int t = m[0][i]; 
            m[0][i] = m[rows - 1][i]; 
            m[rows - 1][i] = t; 
        } 
}  
  
// Driver function 
int main() 
{ 
    // input in the array 
    int m[n][n] = { { 8, 9, 7, 6 }, 
                { 4, 7, 6, 5 }, 
                { 3, 2, 1, 8 }, 
                { 9, 9, 7, 7 } };  
                  
    interchangeFirstLast(m);  
      
    // printing the interchanged matrix 
    for (int i = 0; i < n; i++) 
    { 
        for (int j = 0; j < n; j++)  
            cout << m[i][j] << " "; 
        cout << endl; 
    } 
} 
  
// This code is contributed by Anant Agarwal. 

Java

// Java code to swap the element of first 
// and last row and display the result 
import java.io.*; 
  
public class Interchange { 
      
    static void interchangeFirstLast(int m[][]) 
    { 
        int rows = m.length; 
          
        // swapping of element between first 
        // and last rows 
        for (int i = 0; i < m[0].length; i++) { 
            int t = m[0][i]; 
            m[0][i] = m[rows-1][i]; 
            m[rows-1][i] = t; 
        } 
    } 
      
    // Driver code 
    public static void main(String args[]) throws IOException 
    { 
        // input in the array 
        int m[][] = { { 8, 9, 7, 6 }, 
                    { 4, 7, 6, 5 }, 
                    { 3, 2, 1, 8 }, 
                    { 9, 9, 7, 7 } };  
                      
        interchangeFirstLast(m);  
          
        // printing the interchanged matrix 
        for (int i = 0; i < m.length; i++) { 
            for (int j = 0; j < m[0].length; j++)  
                System.out.print(m[i][j] + " "); 
            System.out.println(); 
        } 
    } 
} 

Python3

# Python code to swap the element 
# of first and last row and display 
# the result 
  
def interchangeFirstLast(mat, n, m): 
    rows = n 
      
    # swapping of element between 
    # first and last rows 
    for i in range(n): 
        t = mat[0][i] 
        mat[0][i] = mat[rows-1][i] 
        mat[rows-1][i] = t 
  
# Driver Program 
mat = [[8, 9, 7, 6], 
          [4, 7, 6, 5], 
       [3, 2, 1, 8], 
       [9, 9, 7, 7]] 
  
n = 4
m = 4
interchangeFirstLast(mat, n, m) 
  
# printing the interchanged matrix 
for i in range(n): 
    for j in range(m): 
        print(mat[i][j], end = " ") 
    print("\n") 
  
# This code is contributed by Shrikant13. 

C#

// C# code to swap the element of first  
// and last row and display the result  
using System; 
  
class GFG 
{ 
  
public static void interchangeFirstLast(int[][] m) 
{ 
    int rows = m.Length; 
  
    // swapping of element between first  
    // and last rows  
    for (int i = 0; i < m[0].Length; i++) 
    { 
        int t = m[0][i]; 
        m[0][i] = m[rows - 1][i]; 
        m[rows - 1][i] = t; 
    } 
} 
  
// Driver code  
public static void Main(string[] args) 
{ 
    // input in the array  
    int[][] m = new int[][] 
    { 
        new int[] {8, 9, 7, 6}, 
        new int[] {4, 7, 6, 5}, 
        new int[] {3, 2, 1, 8}, 
        new int[] {9, 9, 7, 7} 
    }; 
  
    interchangeFirstLast(m); 
  
    // printing the interchanged matrix  
    for (int i = 0; i < m.Length; i++) 
    { 
        for (int j = 0; j < m[0].Length; j++) 
        { 
            Console.Write(m[i][j] + " "); 
        } 
        Console.WriteLine(); 
    } 
} 
} 
  
// This code is contributed by Shrikant13 

PHP

<?php  
// PHP code to swap the element of first 
// and last row and display the result 
$n = 4; 
  
function interchangeFirstLast(&$m) 
{ 
        global $n; 
        $rows = $n; 
           
        // swapping of element between first 
        // and last rows 
        for ($i = 0; $i < $n; $i++) 
        { 
            $t = $m[0][$i]; 
            $m[0][$i] = $m[$rows - 1][$i]; 
            $m[$rows - 1][$i] = $t; 
        } 
}  
   
// Driver function 
  
// input in the array 
$m = array(array(8, 9, 7, 6), 
            array(4, 7, 6, 5), 
            array( 3, 2, 1, 8), 
            array(9, 9, 7, 7));  
               
interchangeFirstLast($m);  
   
// printing the interchanged matrix 
for ($i = 0; $i < $n; $i++) 
{ 
    for ($j = 0; $j < $n; $j++)  
        echo $m[$i][$j] . " "; 
    echo "\n"; 
} 
?> 

Output :

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

C++

Java

Python3

C#

PHP

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