【重点】【矩阵】48.旋转图像

题目

Python

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        # 对角线对调
        for i in range(n):
            for j in range(i+1, n):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]

        # 左右对调
        for i in range(n):
            l, r = 0, n-1
            while l < r:
                matrix[i][l], matrix[i][r] = matrix[i][r], matrix[i][l]
                l += 1
                r -= 1

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        # 左上-右下对角线翻转
        for i in range(n):
            for j in range(i+1, n):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]

        #　竖轴线翻转
        for i in range(n):
            for j in range(n//2):
                matrix[i][j], matrix[i][n-j-1] = matrix[i][n-j-1], matrix[i][j] 

Java

法1：基础好法

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

法2

参考：https://leetcode.cn/problems/rotate-image/solutions/1228078/48-xuan-zhuan-tu-xiang-fu-zhu-ju-zhen-yu-jobi/?envType=study-plan-v2&envId=top-100-liked