题目链接:https://leetcode.com/problems/rotate-image/
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?
思路:
先将矩阵转置,再将矩阵按中轴线对称交换每一列。
算法:
public void rotate(int[][] matrix) { for (int i = 0; i < matrix.length; i++) { //转置 for (int j = i; j < matrix[0].length; j++) { int tmp = matrix[i][j]; matrix[i][j] = matrix[j][i]; matrix[j][i] = tmp; } } for (int i = 0; i < matrix.length; i++) {//交换列 for (int j = 0; j < matrix[0].length / 2; j++) { int tmp = matrix[i][j]; matrix[i][j] = matrix[i][matrix[0].length - 1 - j]; matrix[i][matrix[0].length - 1 - j] = tmp; } } }