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题目： Follow up for "Remove Duplicates":What if duplicates are allowed at most twice? （Medium） For example,Given sorted array nums = [1,1,1,2,2,3], Your 阅读全文
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题目： Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "a 阅读全文
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题目： Given a set of distinct integers, nums, return all possible subsets. Note: The solution set must not contain duplicate subsets. （Medium） For examp 阅读全文
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题目： Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. （Medium） For example,If n = 4 and k = 2, a solution is: 阅读全文