leetcode

1914.cpp (905B)

 class Solution {
   public:
     vector<vector<int>> rotateGrid(vector<vector<int>> &grid, int k) const {
         const int n = size(grid), m = size(grid[0]);
 
         for (int l = 0; l < n / 2 && l < m / 2; l++) {
             const int elems = (m + n - 4 * l - 2) * 2;
             for (int count = 0; count < k % elems; count++) {
                 const int tmp = grid[l][l];
                 for (int j = l + 1; j < m - l; j++)
                     grid[l][j - 1] = grid[l][j];
                 for (int i = l + 1; i < n - l; i++)
                     grid[i - 1][m - l - 1] = grid[i][m - l - 1];
                 for (int j = m - l - 2; j >= l; j--)
                     grid[n - l - 1][j + 1] = grid[n - l - 1][j];
                 for (int i = n - l - 2; i >= l; i--)
                     grid[i + 1][l] = grid[i][l];
                 grid[l + 1][l] = tmp;
             }
         }
 
         return grid;
     }
 };