Leetcode48 Rotate Image

来源：互联网发布：电脑打电话软件下载编辑：程序博客网时间：2024/05/24 23:12

Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Solution1

这道题无非是一些边界条件的把握。

public class Solution {    public void rotate(int[][] matrix) {        int n = matrix.length;        for(int i=0;i<n/2;i++){            for(int j=i;j<n-i-1;j++){                int temp = matrix[i][j];                matrix[i][j] = matrix[n-j-1][i];                matrix[n-j-1][i] = matrix[n-i-1][n-j-1];                matrix[n-i-1][n-j-1] = matrix[j][n-i-1];                matrix[j][n-i-1] = temp;            }        }            }}

Solution2

有更加trick的解法，如下

public class Solution {    public void rotate(int[][] matrix) {        for(int i=0,j=matrix.length-1;i<j;i++,j--){            int[] temp = matrix[i];            matrix[i] = matrix[j];            matrix[j] = temp;        }        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;            }        }    }}

更详细的解释在顺时针和逆时针都可以用类似方法

0 0