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

 1 class Solution {
 2 public:
 3     void rotate(vector<vector<int>>& matrix) {
 4         int i=0;
 5     for(auto iter1=matrix.begin();iter1!=matrix.end();i++,iter1++)
 6     {    int j=i+1;
 7         for(auto iter2=iter1+1;iter2<matrix.end();j++,iter2++)
 8         {
 9             int temp=*((*iter1).begin()+j);
10             *((*iter1).begin()+j)=*((*iter2).begin()+i);
11             *((*iter2).begin()+i)=temp;
12         }
13     }
14     // row to col
15     vector< vector<int> >col_matrix;
16     for(int i=0;i<matrix.size();i++)
17     {
18         vector<int> p;
19         for(int j=0;j<matrix.size();j++)
20         {
21             p.push_back(matrix[j][i]);
22             //*((*(matrix.begin()+i)).begin()+j)=matrix[j][i];
23         }
24         //*(matrix.begin()+i)=p;
25         col_matrix.push_back(p);
26     }
27     matrix=col_matrix;    
28     //reverse
29     reverse(matrix.begin(),matrix.end());
30     //
31     i=0;
32     for(auto iter1=matrix.begin();iter1!=matrix.end();i++,iter1++)
33     {    int j=i+1;
34         for(auto iter2=iter1+1;iter2<matrix.end();j++,iter2++)
35         {
36             int temp=*((*iter1).begin()+j);
37             *((*iter1).begin()+j)=*((*iter2).begin()+i);
38             *((*iter2).begin()+i)=temp;
39         }
40     }
41     }
42 };