Leetcode: Rotate Image

最新推荐文章于 2017-06-03 09:19:48 发布

转载最新推荐文章于 2017-06-03 09:19:48 发布 · 54 阅读

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原文链接：http://www.cnblogs.com/ydlme/p/4586999.html

本文介绍了如何通过先沿对角线对称翻转二维矩阵，然后反转每一行，实现矩阵顺时针旋转90度的操作。重点在于理解旋转过程中的矩阵操作技巧。

Rotate Image

Total Accepted: 37958 Total Submissions: 118891

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?

先按145°对角线将图像对称翻转, 再将各行逆序翻转即可

class Solution {
public:
    void rotate(vector<vector<int> > &matrix) {
        int n = matrix.size();
        for (int y = 1; y < n; y++)
            for (int x = 0; x < y; x++)
                swap(matrix[y][x], matrix[x][y]);
                
        for (auto& sub : matrix)
            reverse(sub.begin(), sub.end());
    }
};

转载于:https://www.cnblogs.com/ydlme/p/4586999.html