随笔分类 - Google
摘要：Design a data structure that supports all following operations in O(1) time. insert(val): Inserts an item val to the set if not already present.remove
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摘要：Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), determine if a person could attend all mee
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摘要：A frog is crossing a river. The river is divided into x units and at each unit there may or may not exist a stone. The frog can jump on a stone, but i
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摘要：Given an integer matrix, find the length of the longest increasing path. From each cell, you can either move to four directions: left, right, up or do
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摘要：Given a string that contains only digits 0-9 and a target value, return all possibilities to add binary operators (not unary) +, -, or *between the di
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摘要：Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may cont
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摘要：There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have t
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摘要：Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist.
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摘要：You are given a m x n 2D grid initialized with these three possible values. -1 - A wall or an obstacle. 0 - A gate. INF - Infinity means an empty room
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摘要：Contains Duplicate I Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at l
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摘要：There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a list of words from the
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摘要：Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating
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摘要：Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of th
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摘要：Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is tha
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摘要：Compare two version numbers version1 and version2.If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0. You may assum
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摘要：Preorder: 因为是preorder traversal, 我们需要先print root，然后左节点，最后右节点，而且root左边子树一定比右边子树先print出来，所以，我们可以先把当前root的右节点压栈，然后把root的左节点压栈，这样每次从栈里取的时候，可以保证左边节点的root先取
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摘要：Validate if a given string is numeric. Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => true Note: It is intended for the
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摘要：Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can f
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摘要：A group of two or more people wants to meet and minimize the total travel distance. You are given a 2D grid of values 0 or 1, where each 1 marks the h
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摘要：Given a binary tree, return the vertical order traversal of its nodes' values. (ie, from top to bottom, column by column). If two nodes are in the sam
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