随笔分类 - Level 2
摘要：Given an array of integers A with even length, return true if and only if it is possible to reorder it such that A[2 * i + 1] = 2 * A[2 * i] for every
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摘要：Solve a given equation and return the value of x in the form of string "x=#value". The equation contains only '+', '-' operation, the variable x and i
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摘要：We are given a list schedule of employees, which represents the working time for each employee. Each employee has a list of non-overlapping Intervals,
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摘要：Given a string, your task is to count how many palindromic substrings in this string. The substrings with different start indexes or end indexes are c
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摘要：Given a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any one of them. Two
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摘要：On a single threaded CPU, we execute some functions. Each function has a unique id between 0 and N-1. We store logs in timestamp order that describe w
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摘要：We are given an array asteroids of integers representing asteroids in a row. For each asteroid, the absolute value represents its size, and the sign r
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摘要：Given a BST, remove an extra edge to make it BST. 7 / \ 5 9 / \ / 3 8
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摘要：A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its inde
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摘要：Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit
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摘要：Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path betwe
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摘要：Given an array with n integers, your task is to check if it could become non-decreasing by modifying at most 1 element. We define an array is non-decr
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摘要：Given an encoded string, return it's decoded string.The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is be
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摘要：You have 4 cards each containing a number from 1 to 9. You need to judge whether they could operated through *, /, +, -, (, ) to get the value of 24.
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摘要：Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words h
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摘要：Given preorder and inorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. For example,
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摘要：TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http
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摘要：Given a sorted array, two integers k and x, find the k closest elements to x in the array. The result should also be sorted in ascending order. If the
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摘要：Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) Yo
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摘要：Given an integer n, return 1 - n in lexicographical order. For example, given 13, return: [1,10,11,12,13,2,3,4,5,6,7,8,9]. Please optimize your algori
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