0048-rotate-image.cpp

class Solution {
 public:
  void rotate(vector<vector<int>>& matrix) {
    transpose(matrix);
    reflect(matrix);
  }

  void transpose(vector<vector<int>>& matrix) {
    int n = matrix.size();
    for (int i = 0; i < n; i++) {
      for (int j = i + 1; j < n; j++) {
        int tmp = matrix[j][i];
        matrix[j][i] = matrix[i][j];
        matrix[i][j] = tmp;
      }
    }
  }

  void reflect(vector<vector<int>>& matrix) {
    int n = matrix.size();
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < n / 2; j++) {
        int tmp = matrix[i][j];
        matrix[i][j] = matrix[i][n - j - 1];
        matrix[i][n - j - 1] = tmp;
      }
    }
  }
};