Rotate Image

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

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

public class Solution {
    public void rotate(int[][] matrix) {
        int len=matrix[0].length;
        for(int i=0;i<len/2;i++){
            int first=i;
            int last=len-i-1;
            
            for(int j=first;j<last;j++){
                int tmp=matrix[first][j];
                
                matrix[first][j]=matrix[last-j+first][first];//left to up
                
                matrix[last-j+first][first]=matrix[last][last-j+first];//down to left
                
                matrix[last][last-j+first]=matrix[j][last];//right to down
                
                matrix[j][last]=tmp;//up to right
                
            }
        }
    }
}