Rotate matrix by clockwise

Rotate matrix by clockwise

Rotate matrix by clockwise  

Given a NxN matrix and need to rotate by clockwise as given below

Examples:

Let's see simple java code to rotate given NxN matrix.

public class MatrixRotate {

 private int prev, curr;

 public static void main(String[] args) {

  int[][] matrix = new int[][] { { 1, 2, 3, 4 }, 
                   { 5, 6, 7, 8 }, 
            { 9, 10, 11, 12 }, 
            { 13, 14, 15, 16 } };
  

  MatrixRotate obj = new MatrixRotate();
  obj.rotateMatrix(matrix);

  for (int i = 0; i < matrix.length; i++) {
   System.out.println();
   for (int j = 0; j < matrix[0].length; j++) {
    System.out.print(matrix[i][j] + ", ");
   }
  }
 }

 public void rotateMatrix(int[][] matrix) {

  int r = matrix.length;
  int c = matrix[0].length;
  int row = 0, col = 0;

  for (int cnt = 0;cnt<(r*c);cnt++) {
   
   prev = matrix[row + 1][col];

   for (int i = col; i < c; i++) {
    swap(row, i, matrix); cnt++;   }
   row++;

   for (int i = row; i < r; i++) {
    swap(i, c - 1, matrix); cnt++;   }
   c--;

   if (row < r) {
    for (int i = c - 1; i >= col; i--) {
     swap(r - 1, i, matrix); cnt++;
    }
   }
   r--;

   if (col < c) {
    for (int i = r - 1; i >= row; i--) {
     swap(i, col, matrix); cnt++;
    }
   }
   col++;
  }
 }

 public void swap(int i, int j, int matrix[][]) {
  curr = matrix[i][j];
  matrix[i][j] = prev;
  prev = curr;
 }
}

OUTPUT:

 5,  1,  2,  3, 
 9, 10,  6,  4, 
13, 11,  7,  8, 
14, 15, 16, 12,