Rotate Image.cpp

/*
You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).
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.
*/

class Solution {
public:
    void rotate(vector<vector<int>>& matrix) {
        int n = matrix.size();
        //Transpose the matrix
        for(int i=0;i<n;i++){
            for(int j=0;j<i;j++){
                swap(matrix[i][j], matrix[j][i]);
            }
        }
        //reverse the matrix
        for(int i=0;i<n;i++){
            reverse(matrix[i].begin(), matrix[i].end());
        }
    }
};