摘要：Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: "
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摘要：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.
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摘要：Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the
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摘要：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. After rem
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摘要：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 whic
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摘要：Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telepho
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摘要：Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers.
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摘要：Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of
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摘要：Write a function to find the longest common prefix string amongst an array of strings.
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摘要：Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.
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摘要：Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
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摘要：Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpo
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摘要：Implement regular expression matching with support for '.' and '*'. 思路：在出现*的时候，因为可能出现0，1，2，...次，所以要使用到带回溯的递归
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摘要：Determine whether an integer is a palindrome. Do this without extra space.
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摘要：Implement atoi to convert a string to an integer. If no valid conversion could be performed, a zero value is returned. If the correct value is out of
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摘要：Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 For the purpose of this problem, assume that your function
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摘要：The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font
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摘要：Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longes
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摘要：There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity sh
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摘要：Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters fo
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