Java Program for Rotate the matrix right by K times

0 1 2 minutes read

Given a matrix of size N*M, and a number K. We have to rotate the matrix K times to the right side.
Examples:

Input :  N = 3, M = 3, K = 2
         12 23 34
         45 56 67
         78 89 91 

Output : 23 34 12
         56 67 45
         89 91 78 


Input :  N = 2, M = 2, K = 2
         1 2
         3 4
         
Output : 1 2
         3 4

A simple yet effective approach is to consider each row of the matrix as an array and perform an array rotation. This can be done by copying the elements from K to end of array to starting of array using temporary array. And then the remaining elements from start to K-1 to end of the array.
Lets take an example:

Java

// Java program to rotate a matrix
// right by k times
 
class GFG
{
    // size of matrix
    static final int M=3;
    static final int N=3;
     
    // function to rotate matrix by k times
    static void rotateMatrix(int matrix[][], int k)
    {
        // temporary array of size M
        int temp[]=new int[M];
         
        // within the size of matrix
        k = k % M;
         
        for (int i = 0; i < N; i++)
        {
         
            // copy first M-k elements
            // to temporary array
            for (int t = 0; t < M - k; t++)
            temp[t] = matrix[i][t];
         
            // copy the elements from k
            // to end to starting
            for (int j = M - k; j < M; j++)
            matrix[i][j - M + k] = matrix[i][j];
         
            // copy elements from
            // temporary array to end
            for (int j = k; j < M; j++)
            matrix[i][j] = temp[j - k];
        }
    }
     
    // function to display the matrix
    static void displayMatrix(int matrix[][])
    {
        for (int i = 0; i < N; i++)
        {
            for (int j = 0; j < M; j++)
            System.out.print(matrix[i][j] + " ");
            System.out.println();
        }
    }
     
    // Driver code
    public static void main (String[] args)
    {
        int matrix[][] = {{12, 23, 34},
                        {45, 56, 67},
                        {78, 89, 91}};
    int k = 2;
     
    // rotate matrix by k
    rotateMatrix(matrix, k);
     
    // display rotated matrix
    displayMatrix(matrix);
    }
}
 
// This code is contributed by Anant Agarwal.