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题目描述：Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.解题思路... 阅读全文
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题目描述：Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in ... 阅读全文
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题目描述：Given a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. A... 阅读全文
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问题描述：Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array... 阅读全文
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题目描述：Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the tel... 阅读全文