[leetcode刷题系列]Rotate Image

算是模拟题把， 至于in-place，简单想下就好了， 规律还是很容易发现的。只是写的时候下标要想清楚，别写错。

class Solution {    void change(int &a, int &b, int &c, int &d){        int tmp = d;        d = c;        c = b;        b = a;        a = tmp;    }public:    void rotate(vector<vector<int> > &matrix) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        int n = matrix.size();        for(int i = 0;i < n / 2; ++ i){            for(int j = i; j + i + 1 < n; ++ j)                change(matrix[i][j], matrix[j][n - 1 -i], matrix[n - 1 - i][n - 1 -j], matrix[n - 1 - j][i]);        }    }};