leetcode 48. Rotate Image

Seawolf

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Note:

You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Example 1:

Given input matrix = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],

rotate the input matrix in-place such that it becomes:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]
Example 2:

Given input matrix =
[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 

rotate the input matrix in-place such that it becomes:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]

class Solution {
    public void rotate(int[][] matrix) {
        if(matrix.length == 0) return;
        int row = matrix.length -1;
        int col = matrix[0].length -1;
        int repeat = 0;
        for(int i = 0 ; i <= row/2; i++){
            
            for(int j = 0 ; j <= col /2 ; j++){
                
                if(row % 2 == 0 && i == row/2 && j != col/2) continue;
                swap(matrix, i ,j);
                
            }
        }
    }
    
    public void swap(int[][] matrix, int i, int j){
        int row = matrix.length - 1;
        int col = matrix[0].length - 1;
        
        int temp = matrix[i][j];
        matrix[i][j] = matrix[row - j][i];
        matrix[row- j][i] = matrix[row-i][col - j];
        matrix[row- i][col - j] = matrix[j][col - i];
        matrix[j][col- i] = temp;
        
    }
    
}