LeetCode 2nd time 48. 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?

More intuitive solution.
With up left index and bottom right index layer by layer
Each outer iteration will rotate one layer and after that upleft index -- and bottomright index++, we proceed to process next layer.

  public void rotate(int[][] matrix) {  
     int n=matrix.length;  
     int upleft=0;  
     int bottomright=n-1;  
    while(upleft<bottomright){  
        for(int j=upleft;j<bottomright;j++){  
         int temp=matrix[upleft][j];  
         matrix[upleft][j]=matrix[n-j-1][upleft];  
         matrix[n-j-1][upleft]=matrix[bottomright][n-j-1];  
         matrix[bottomright][n-j-1]=matrix[j][bottomright];  
         matrix[j][bottomright]=temp;  
       }  
       upleft++;  
       bottomright--;  
     }  
   }