Rotate Image

Question:

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

Solution

class Solution {
public:
    void rotate(vector<vector<int>>& matrix) {
        int i=0;
    for(auto iter1=matrix.begin();iter1!=matrix.end();i++,iter1++)
    {    int j=i+1;
        for(auto iter2=iter1+1;iter2<matrix.end();j++,iter2++)
        {
            int temp=*((*iter1).begin()+j);
            *((*iter1).begin()+j)=*((*iter2).begin()+i);
            *((*iter2).begin()+i)=temp;
        }
    }
    // row to col
    vector< vector<int> >col_matrix;
    for(int i=0;i<matrix.size();i++)
    {
        vector<int> p;
        for(int j=0;j<matrix.size();j++)
        {
            p.push_back(matrix[j][i]);
            //*((*(matrix.begin()+i)).begin()+j)=matrix[j][i];
        }
        //*(matrix.begin()+i)=p;
        col_matrix.push_back(p);
    }
    matrix=col_matrix;    
    //reverse
    reverse(matrix.begin(),matrix.end());
    //
    i=0;
    for(auto iter1=matrix.begin();iter1!=matrix.end();i++,iter1++)
    {    int j=i+1;
        for(auto iter2=iter1+1;iter2<matrix.end();j++,iter2++)
        {
            int temp=*((*iter1).begin()+j);
            *((*iter1).begin()+j)=*((*iter2).begin()+i);
            *((*iter2).begin()+i)=temp;
        }
    }
    }
};