Rotate Image

Rotate Image (link)Mar 18 '12

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?

class Solution {
public:
    void rotate(vector<vector<int> > &matrix) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (matrix.empty() || matrix[0].empty() ) return;
        int const max = matrix.size() - 1;
        int const quarter_col_size = matrix.size() / 2 + (matrix.size()%2);
        int const quarter_row_size = matrix.size() / 2;
        for(int row = 0; row < quarter_row_size; ++row){
            for(int col = 0; col < quarter_col_size; ++col){
                int const temp = matrix[row][col];
                matrix[row][col] = matrix[max-col][row];
                matrix[max-col][row] = matrix[max-row][max-col];
                matrix[max-row][max-col] = matrix[col][max-row];
                matrix[col][max-row] = temp;
            }
        }
    }
};