Interchange elements of first and last rows in matrix

Given a 4 x 4 matrix, we have to interchange the elements of the 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 6 1 2
              2 7 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

Interchange elements of first and last rows in the matrix using the swap function:

To solve the problem follow the below idea:

The approach is very simple, we can simply swap the elements of the first and last row of the matrix in order 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 code
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 } };

    // Function call
    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 } };

        // Function call
        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

# Python3 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 code
if __name__ == "__main__":
    mat = [[8, 9, 7, 6],
           [4, 7, 6, 5],
           [3, 2, 1, 8],
           [9, 9, 7, 7]]

    n = 4
    m = 4

    # Function call
    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 } };

        // Function call
        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 code

// 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));

// Function call
interchangeFirstLast($m);

// printing the interchanged matrix
for ($i = 0; $i < $n; $i++)
{
    for ($j = 0; $j < $n; $j++)
        echo $m[$i][$j] . " ";
    echo "\n";
}
?>

Javascript

<script>
// Javascript code to swap the element of first
// and last row and display the result

    function interchangeFirstLast(m)
    {
        let rows = m.length;

        // swapping of element between first
        // and last rows
        for (let i = 0; i < m[0].length; i++) {
            let t = m[0][i];
            m[0][i] = m[rows-1][i];
            m[rows-1][i] = t;
        }
    }

    // Driver code

    // input in the array
    let m = [[8, 9, 7, 6],
          [4, 7, 6, 5],
       [3, 2, 1, 8],
       [9, 9, 7, 7]]
        interchangeFirstLast(m);

     // printing the interchanged matrix
     for (let i = 0; i < m.length; i++) {
        for (let j = 0; j < m[0].length; j++)
            document.write(m[i][j] + " ");
        document.write("<br>");
     }


    // This code is contributed by avanitrachhadiya2155
</script>

Output

9 9 7 7 
4 7 6 5 
3 2 1 8 
8 9 7 6 

Time Complexity: O(N)
Auxiliary Space: O(1)