# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 48: Rotate Imagehttps://leetcode.com/problems/rotate-image/ You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Could you do this in-place? ===…

leetcode - 48. Rotate Image - Medium descrition You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix direct…

一.题目说明 题目是48. Rotate Image,简而言之就是矩阵顺时针旋转90度.不允许使用额外的矩阵. 经过观察(写一个矩阵,多看几遍就知道了),旋转90度后: 第1行变为len-1列(最后一列),第i行变为 len-i-1列最终达到(i,j)-->(j,len-i-1) 知道规律后,做法就比较简单了,可以先上下行交换,再对角交换: (i,j)-->(len-i-1,j)-->(j,len-i-1) 也可以先对角交换,再左右列交换: (i,j)-->(j,i)-->(…

Question 48. Rotate Image Solution 把这个二维数组(矩阵)看成一个一个环,循环每个环,循环每条边,每个边上的点进行旋转 public void rotate(int[][] matrix) { int n = matrix.length; for (int i = 0; i < n / 2; i++) { change(matrix, i); } } private void change(int[][] matrix, int i) { int n = mat…

  You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note:You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do th…

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the…

1 题目 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? 2 思路 使用辅助空间比较简单. 不使用辅助空间,想了半天,没想出来.. 看别人的代码,原来是要翻转两次.. 3 代码 public void rotate(int[][] matrix) { // 使用多余空间的…

题目: 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? 链接:  http://leetcode.com/problems/rotate-image/ 题解: in-place,按照顺时针移动整个矩阵的1/4,注意边长为奇数时的corner case. 还有方法是对折再变…

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? 思路:事实上就是旋转数组.没有什么难度.代码例如以下: public class Solution { public void rotate(int[][] matrix) { int[][] a…

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? [题目解析] 这个题目的要求是把一个二维数组向右旋转九十度,就地实现. [思路1] 相比较矩阵的转置,矩阵的旋转有什么不同呢?看下面的例子: 1,2,3 1,3,2      1,2,3 2,3,1 3,2,1    ---…

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? 题目标签:Array 这道题目给了我们一个n * n的矩阵,让我们旋转图片.题目要求in-place,所以就不能用额外的空间了.一开始自己写了一个很原始的方法,结果虽然通过,但是速度太慢.只好去看看别人的方法,看完觉得,自己…

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? 方阵顺时针旋转90度,方法: 按行reverse 交换元素 A[i, j] = A[j, i] 逆时针90度方法: 按列reverse for (auto vi : matrix) reverse(vi.begin(),…

一天一道LeetCode系列 (一)题目 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? (二)解题 90度旋转图像,我们不难看出 经过这样的变换后,图像就旋转了90度. class Solution { public: void rotate(vector<vecto…

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the…

You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise). Note:You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the r…

题目链接: https://leetcode.com/problems/rotate-image/?tab=Description   Problem:给定一个n*n的二维图片,将这个二维图片按照顺时针旋转90°   求解过程:   参考链接 https://discuss.leetcode.com/topic/9744/ac-java-in-place-solution-with-explanation-easy-to-understand   求解过程如下所示:     首先对矩阵进行按照对…

题目大意:给一个矩阵,将其按顺时针旋转90°. 题目分析:通法是先将矩阵转置,然后再反转每一行,或者是先反转每一列,然后再将其转置.I just want to say"It's amazing!".(forgivig my poor English!) 代码如下(代码怎么写已经不重要了!): class Solution { public: void rotate(vector<vector<int>>& matrix) { int r=matrix.…

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? 最简单的想法,两重循环. 第一重循环是对于矩阵的层次(从外到内) 第二重循环是对于每一层次的四元素轮换 举例: 1 2 3 4 5 6 7 8 9 最外层: 1-->3-->9-->7 2…

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) { int temp; ; i < matrix.size(…

题目: You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do…

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOTallocate another 2D matrix and do the…

Difficulty:medium  More:[目录]LeetCode Java实现 Description 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). Note: You have to rotate the image in-place, which…

题目描述:把一个二维数组顺时针旋转90度: 思路: 对于数组每一圈进行旋转,使用m控制圈数: 每一圈的四个元素顺时针替换,可以直接使用Python的解包,使用k控制每一圈的具体元素: class Solution(object): def rotate(self, matrix): """ :type matrix: List[List[int]] :rtype: void Do not return anything, modify matrix in-place inst…

题意 原地顺时针翻转一个 n*n 的矩阵 图解 下面例子中用 5*5 矩阵做示例,如下图,我们要把该矩阵顺时针翻转90度,并且不能使用另外的矩阵空间来暂存数据,而是原地改变矩阵中数值. 我的想法是这样的:找出翻转的下标变换规律,找出需要变换的位置,将与该位置有关的四个方法(left, top, right, bottom)一次性交换值. 如下图: 首先我从最外围入手,其实整个外围的变化,可以以第一行的 (0, n-2)坐标的元素为基础开始变化,其他三个方向是跟它有关的需要同时变换的元素: 同理,…

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 日期 题目地址:https://leetcode.com/problems/rotate-image/description/ 题目描述 You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: Y…

48. Rotate Image     Total Accepted: 69437 Total Submissions: 198781 Difficulty: Medium You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). 显然的,矩阵旋转. 这里我是多开一个数组来直接赋值,没有原地翻转. 或许原地翻转能更快. package leetcode.…

48. Rotate Image 先按对角线对称图形,再水平对折. class Solution { public void rotate(int[][] matrix) { //1.transpose for(int i = 0; i < matrix.length; i++){ for(int j = 0; j < i; j++){ int temp = matrix[i][j]; matrix[i][j] = matrix[j][i]; matrix[j][i] = temp; } }…

Given a linked list, rotate the list to the right by k places, where k is non-negative. Example 1: Input: 1->2->3->4->5->NULL, k = 2 Output: 4->5->1->2->3->NULL Explanation: rotate 1 steps to the right: 5->1->2->3-&g…

package y2019.Algorithm.array.medium; import java.util.*; /** * @ProjectName: cutter-point * @Package: y2019.Algorithm.array.medium * @ClassName: CombinationSum * @Author: xiaof * @Description: TODO 39. Combination Sum * Given a set of candidate numb…