[Leetcode] Rotate Matrix

Rotate a matrix for 90 degree in clockwise. 

public void rotate(int[][] matrix) {     int n = matrix[0].length;      for (int i = 0; i < Math.floor(n/2) ; i++) {      for (int j = i; j < n-1-i; j++) {        int temp = matrix[i][j];         matrix[i][j] = matrix[n-1-j][i];         matrix[n-1-j][i] = matrix[n-1-i][n-1-j];         matrix[n-1-i][n-1-j] = matrix[j][n-1-i];         matrix[j][n-1-i] = temp;       }     }    }

This is how I did after stupid thinking for hours T^T. 

But I think this's the most elegant solution which has the smallest time and space complex.