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
// Java Program to Interchange Elements of First// and Last Row in a Matrix// Importing input output classesimport java.io.*;// Main Classpublic 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)
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