LeetCode-48.Rotate Image

https://leetcode.com/problems/rotate-image/

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?

public void Rotate(int[,] matrix) 
    {
        int n = (int)matrix.GetLongLength(0);
        int begin=0,end=n-1,num,off;
        for (int layer = 0; layer < n/2; layer++)
        {
            for (int i = begin; i < end; i++)
            {
                off = i - begin;
                num = matrix[begin, i];
                matrix[begin, i] = matrix[end - off, begin];
                matrix[end - off, begin] = matrix[end, end - off];
                matrix[end, end - off] = matrix[i, end];
                matrix[i, end] = num;
            }
            begin++;
            end--;
        }
    }

《程序员面试金典》P114原题