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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
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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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Given a 2D grid, each cell is either a wall 'W', an enemy 'E' or empty '0' (the number zero), return the maximum enemies you can kill using one bomb.T 阅读全文
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You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u,v) which consists of one element from th 阅读全文
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You are playing the following Flip Game with your friend: Given a string that contains only these two characters: + and -, you and your friend take tu 阅读全文
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Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at 阅读全文