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You are given two string arrays words1 and words2. A string b is a subset of string a if every letter in b occurs in a including multiplicity. For exa 阅读全文
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A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possibl 阅读全文
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Design a data structure that simulates an in-memory file system. Implement the FileSystem class: FileSystem() Initializes the object of the system. Li 阅读全文
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A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the di 阅读全文
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Given a string s and an array of strings words, return the number of words[i] that is a subsequence of s. A subsequence of a string is a new string ge 阅读全文
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You are given an array of strings products and a string searchWord. Design a system that suggests at most three product names from products after each 阅读全文
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You are given two string arrays username and website and an integer array timestamp. All the given arrays are of the same length and the tuple [userna 阅读全文
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Let's define a function countUniqueChars(s) that returns the number of unique characters on s. For example, calling countUniqueChars(s) if s = "LEETCO 阅读全文
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You are given an integer array nums. The range of a subarray of nums is the difference between the largest and smallest element in the subarray. Retur 阅读全文
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Given an array of integers arr, find the sum of min(b), where b ranges over every (contiguous) subarray of arr. Since the answer may be large, return 阅读全文
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Given two nodes of a binary tree p and q, return their lowest common ancestor (LCA). Each node will have a reference to its parent node. The definitio 阅读全文
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A string can be abbreviated by replacing any number of non-adjacent, non-empty substrings with their lengths. The lengths should not have leading zero 阅读全文
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You are implementing a program to use as your calendar. We can add a new event if adding the event will not cause a double booking. A double booking h 阅读全文
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A car travels from a starting position to a destination which is target miles east of the starting position. There are gas stations along the way. The 阅读全文
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A parentheses string is a non-empty string consisting only of '(' and ')'. It is valid if any of the following conditions is true: It is (). It can be 阅读全文
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In a linked list of size n, where n is even, the ith node (0-indexed) of the linked list is known as the twin of the (n-1-i)th node, if 0 <= i <= (n / 阅读全文
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Given a string s, find the longest palindromic subsequence's length in s. A subsequence is a sequence that can be derived from another sequence by del 阅读全文
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Given a non-empty array nums containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in 阅读全文
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Given a string S with only lowercase characters. Return the number of substrings that contains at least k distinct characters. Example 1: Input: S = " 阅读全文
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There is a row of n houses, where each house can be painted one of three colors: red, blue, or green. The cost of painting each house with a certain c 阅读全文