LeetCode --- Rotate Image

题目链接

题意：　给出 n * n的矩阵，要求将矩阵顺时针旋转９０°（不使用额外空间）

 1 /*

 2  Basically, divide the array into 4 along the diagonals,  3  then for each element in the top quadrant, place it into  4  the slot 90 degrees cw, and the old 90 in 180 degrees cw,  5  and the old 180 in 270 degrees , and the old 270 in  6  the original place.  7  */

 8 class Solution {  9 public: 10     void rotate(vector<vector<int> > &matrix) { 11         int n = (int)matrix.size(); 12         for (int i = 0; i < n/2; i++) for (int j = i; j < n-1-i; j++) { 13                 swap(matrix[i][j], matrix[j][n-1-i]); 14                 swap(matrix[i][j], matrix[n-1-i][n-1-j]); 15                 swap(matrix[i][j], matrix[n-1-j][i]); 16  } 17  } 18 };