Rotate Image

Question

class Solution {
public:
    void rotate(vector<vector<int> >& matrix) {

    for(int layer=0;layer<matrix.size()/2;++layer){     //View matrix like many circles
        int row=matrix.size()-2*layer;
        int col=row;
        for(int i=0;i<col-1;++i){
        int tmp=matrix[layer][layer+i];
        matrix[layer][layer+i]=matrix[row-1-i+layer][layer];
        matrix[row-1-i+layer][layer]=matrix[row-1+layer][row-1-i+layer];
        matrix[row-1+layer][row-1-i+layer]=matrix[i+layer][row-1+layer];
        matrix[i+layer][row-1+layer]=tmp;
        }
    }

    }
};