Java Program to Interchange Elements of First and Last in a Matrix Across Rows
Last Updated :
27 Sep, 2022
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For a given 4 × 4 matrix, the task is to interchange the elements of the first and last rows and then return the resultant matrix.
Illustration:
Input 1: 1 1 5 0
2 3 7 2
8 9 1 3
6 7 8 2
Output 1: 6 7 8 2
2 3 7 2
8 9 1 3
1 1 5 0
Input 2: 7 8 9 10
11 13 14 1
15 7 12 22
11 21 30 1
Output 2: 11 21 30 1
11 13 14 1
15 7 12 22
7 8 9 10
Approach:
To get the required output, we need to swap the elements of the first and the last row of the stated matrix.
Example
// Java Program to Interchange Elements of First
// and Last Row in a Matrix
// Importing input output classes
import java.io.*;
// Main Class
public class GFG {
// Method 1
// To swap First and Last Row
static void swap_First_last(int mat[][])
{
int rws = mat.length;
// Interchanging of elements between the
// first and last rows
for (int j = 0; j < mat[0].length; j++) {
// Using temporary variable so in order
// not to lose the values of the matrix
// Simply, swapping the values stored
int temp = mat[0][j];
mat[0][j] = mat[rws - 1][j];
mat[rws - 1][j] = temp;
}
}
// Method 2
// Main driver method
public static void main(String args[])
throws IOException
{
// Input integer matrix
int mat[][] = { { 2, 3, 4, 5 },
{ 8, 9, 6, 15 },
{ 13, 22, 11, 18 },
{ 19, 1, 2, 0 } };
// Display message only
System.out.println("Input matrix is as follows : ");
// Printing the Input matrix
for (int j = 0; j < mat.length; j++) {
for (int k = 0; k < mat[0].length; k++)
// Print the elements of the input matrix
System.out.print(mat[j][k] + " ");
// New line as row ended
System.out.println();
}
System.out.println(
"Swapped matrix is as follows : ");
// Calling the (method1) to swap rows in a matrix
swap_First_last(mat);
// Printing the Swapped matrix
for (int j = 0; j < mat.length; j++) {
for (int k = 0; k < mat[0].length; k++)
// Print the elements of the swapped matrix
System.out.print(mat[j][k] + " ");
// New line as row ended
System.out.println();
}
}
}
Output:
Input matrix is as follows : 2 3 4 5 8 9 6 15 13 22 11 18 19 1 2 0 Swapped matrix is as follows : 19 1 2 0 8 9 6 15 13 22 11 18 2 3 4 5
Time Complexity: O(n*m) where n and m are numbers of rows and columns respectively.
Auxiliary Space: O(1)
