Study Plan For Algorithms - Part24

1. 全排列 II
题目链接：https://leetcode.cn/problems/permutations-ii/
给定一个可包含重复数字的序列 nums ，按任意顺序 返回所有不重复的全排列。

class Solution:
    def permuteUnique(self, nums: List[int]) -> List[List[int]]:
        def backtrack(nums, path, res, used):
            if len(path) == len(nums):
                res.append(path)
                return
            for i in range(len(nums)):
                if used[i] or (i > 0 and nums[i] == nums[i - 1] and not used[i - 1]):
                    continue
                used[i] = True
                backtrack(nums, path + [nums[i]], res, used)
                used[i] = False

        nums.sort()
        res = []
        used = [False] * len(nums)
        backtrack(nums, [], res, used)
        return res

2. 旋转图像
题目链接：https://leetcode.cn/problems/rotate-image/
给定一个 n × n 的二维矩阵 matrix 表示一个图像。请将图像顺时针旋转 90 度。

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        for i in range(n // 2):
            for j in range(i, n - i - 1):
                temp = matrix[i][j]
                matrix[i][j] = matrix[n - 1 - j][i]
                matrix[n - 1 - j][i] = matrix[n - 1 - i][n - 1 - j]
                matrix[n - 1 - i][n - 1 - j] = matrix[j][n - 1 - i]
                matrix[j][n - 1 - i] = temp