随笔分类 - LeetCode
摘要：Implement a trie with insert, search, and startsWith methods. Note:You may assume that all inputs are consist of lowercase letters a-z. 解法： Trie（字典树）的
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摘要：Given an integer matrix, find the length of the longest increasing path. From each cell, you can either move to four directions: left, right, up or do
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摘要：Given a singly linked list, return a random node's value from the linked list. Each node must have the same probability of being chosen. Follow up: Wh
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摘要：Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number m
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摘要：Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers. If such arrangement is not possib
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摘要：You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a conca
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摘要：Divide two integers without using multiplication, division and mod operator. If it is overflow, return MAX_INT. 解法： 这道题让我们求两数相除，而且规定我们不能用乘法，除法和取余操作。 采
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摘要：Implement strStr(). Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. 解法： 这道题让我们在一个字符串中找另一个字符串
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摘要：Given an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for another array, you
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摘要：Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space fo
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摘要：Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. k is a positive integer and is less than or equal to
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摘要：Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2->3->4, you should return the list as 2->1->4->3. Your
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摘要：Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 解法1： 采用递归的方法，不管合并几个，归根到底还是需要两两合并。 首先想到的是前两个先合并，然后再跟
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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: 解
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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. 解法： 新建一个
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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, Note:Given n will always be valid.Try to do this in on
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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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