Interchange elements of first and last rows in matrix - GeeksforGeeks

06 May, 2021
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 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
 
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++
Java
Python3
C#
PHP
Javascript
// 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 functionint 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 code to swap the element of first// and last row and display the resultimport 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();        }    }}
# 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 Programmat = [[8, 9, 7, 6],          [4, 7, 6, 5],       [3, 2, 1, 8],       [9, 9, 7, 7]] n = 4m = 4interchangeFirstLast(mat, n, m) # printing the interchanged matrixfor i in range(n):    for j in range(m):        print(mat[i][j], end = " ")    print("\n") # This code is contributed by Shrikant13.
// C# code to swap the element of first// and last row and display the resultusing 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 codepublic 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 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($m);  // printing the interchanged matrixfor ($i = 0; $i < $n; $i++){    for ($j = 0; $j < $n; $j++)        echo $m[$i][$j] . " ";    echo "\n";}?>
<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 
 
shrikanth13
ukasp
don283978
avanitrachhadiya2155
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Matrix
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