1.6数组 像素翻转

class Transform {
public:
    vector<vector<int> > transformImage(vector<vector<int> > mat, int n)
    {
        for(int layer=0;layer<n/2;++layer)
        {
            int first=layer;
            int last=n-1-layer;
            for(int i=first;i<last;++i)
            {
                int offset=i-first;
                //存储上边
                int top=mat[first][i];
                //左到上
                mat[first][i]=mat[last-offset][first];
                //下到左
                mat[last-offset][first]=mat[last][last-offset];
                //右到下
                mat[last][last-offset]=mat[i][last];
                //上到右
                mat[i][last]=top;
            }
        }
        return mat;
    }
};