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Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges mak 阅读全文
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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 阅读全文
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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. 阅读全文
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Strobogrammatic Number I A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function t 阅读全文
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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 阅读全文
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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 阅读全文
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Construct minimum number by reordering a given non-negative integer array. Arrange them such that they form the minimum number. Notice The result may 阅读全文
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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 阅读全文
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Given a binary tree, find the largest subtree which is a Binary Search Tree (BST), where largest means subtree with largest number of nodes in it. Not 阅读全文
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For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible roote 阅读全文