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?

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