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Given an 2D board, count how many battleships are in it. The battleships are represented with 'X's, empty slots are represented with '.'s. You may ass 阅读全文
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You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1' 阅读全文
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Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find 阅读全文
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Given an integer, return its base 7 string representation. Example 1: Example 2: Note: The input will be in range of [-1e7, 1e7]. 阅读全文
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Given a binary search tree (BST) with duplicates, find all the mode(s) (the most frequently occurred element) in the given BST. Assume a BST is define 阅读全文
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The API: int read4(char *buf) reads 4 characters at a time from a file. The return value is the actual number of characters read. For example, it retu 阅读全文