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Promble link: https://leetcode.com/problems/permutations/ Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. Input: nums = [1,2,3] Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]] Input: nums = [0,1] Output: [[0,1],[1,0]] Input: nums = [1] Output: [[1]] Approa...

itertools 为高效循环而创建迭代器的函数 link: https://docs.python.org/zh-cn/3.10/library/itertools.html 无穷迭代器 count() cycle() repeat() count(start=0, step=1) Make an iterator that returns evenly spaced values starting with number start. count(10) --> 10 11 12 13 14 ... 根据最短输入序列长度停止的迭代器 groupby() groupby(iterable, key=None) 创建一个迭代器，返回 ...

Promble link: https://leetcode.com/problems/4sum/ Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that: 0 <= a, b, c, d < n a, b, c, and d are distinct. nums[a] + nums[b] + nums[c] + nums[d] == target You may return the answer in any order. Input: nums =...

Promble link: https://leetcode.com/problems/combinations/description/ Given two integers n and k, return all possible combinations of k numbers chosen from the range [1, n]. You may return the answer in any order. Input: n = 4, k = 2 Output: [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] Explanation: There are 4 choose 2 = 6 total combinations. Note ...

Promble link: https://leetcode.com/problems/combination-sum-iii/ Find all valid combinations of k numbers that sum up to n such that the following conditions are true: Only numbers 1 through 9 are used. Each number is used at most once. Return a list of all possible valid combinations. The list must not contain the same combination twice, and...

Promble Link: https://leetcode.com/problems/wiggle-subsequence/description/ A wiggle sequence is a sequence where the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with one element and a sequence with two non-equal ele...

Promble link: https://leetcode.com/problems/remove-element/description/ Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val. Consider the number of elements in nums which are not equal to ...

Promble link: https://leetcode.com/problems/container-with-most-water/ You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]). Find two lines that together with the x-axis form a container, such that the container contains the most water. R...