Tutorialspoint.dev

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


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(" ")
  
# 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 " ";
}
?>


Output :

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


This article is attributed to GeeksforGeeks.org

leave a comment

code

0 Comments

load comments

Subscribe to Our Newsletter