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(),…

# -*- 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 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    ---…