A simple and in-place idea: first reverse the image in row-major order and then transpose it :-)
1 class Solution { 2 public: 3 void rotate(vector<vector<int>>& matrix) { 4 reverse(begin(matrix), end(matrix)); 5 int m = matrix.size(), n = matrix[0].size(); 6 for (int i = 0; i < m; i++) 7 for (int j = 0; j < i; j++) 8 swap(matrix[i][j], matrix[j][i]); 9 } 10 };
