LeetCode——048

/*
48. Rotate Image My Submissions QuestionEditorial Solution
Total Accepted: 66533 Total Submissions: 192145 Difficulty: Medium
You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

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Could you do this in-place?

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*/
/*
解题思路：
1.将矩阵沿副对角线对折交换
2.将上一步得到的矩阵按行对折交换
*/

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

        //首先将矩阵沿副对角线进行交换

        int n=matrix.size();
        if(n==0)return ;
        for(int i=0;i<n;i++){

            for(int j=0;j<n-i;j++){

                swap(matrix[i][j],matrix[n-j-1][n-i-1]);
            }
        }

        //将矩阵行对称调换
        for(int i=0;i<n/2;i++){

            swap(matrix[i],matrix[n-i-1]);
        }


    }
};