Leetcode Rotate Image

class Solution {
public:
    void rotate(vector<vector<int> > &matrix) {
        int n = matrix.size();
        for(int i = 0 ;i  < n/2; ++ i){
            for(int j = i; j < n - i-1; ++ j){
                swap(matrix[i][j],matrix[j][n-i-1]); 
                swap(matrix[i][j],matrix[n-i-1][n-j-1]);
                swap(matrix[i][j],matrix[n-j-1][i]);
            }
        }
    }
};