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Alex and Lee play a game with piles of stones. There are an even number of piles arranged in a row, and each pile has a positive integer number of sto 阅读全文
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A permutation perm of n + 1 integers of all the integers in the range [0, n] can be represented as a string s of length n where: s[i] == 'I' if perm[i 阅读全文
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Given a n * n matrix grid of 0's and 1's only. We want to represent the grid with a Quad-Tree. Return the root of the Quad-Tree representing the grid. 阅读全文
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You are the manager of a basketball team. For the upcoming tournament, you want to choose the team with the highest overall score. The score of the te 阅读全文
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Given a 2D grid consists of 0s (land) and 1s (water). An island is a maximal 4-directionally connected group of 0s and a closed island is an island to 阅读全文