02 2017 档案
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：水塘抽样是一系列的随机算法，其目的在于从包含n个项目的集合S中选取k个样本，其中n为一很大或未知的数量，尤其适用于不能把所有n个项目都存放到主内存的情况。 在高德纳的计算机程序设计艺术中，有如下问题：可否在一未知大小的集合中，随机取出一元素？。或者是Google面试题： I have a linke
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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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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. 解法: 广度优先搜索：先比较所有字符串的第一个字符，然后比较第二个。。。。如果某一行没有了（说明其为最短的单词）或者遇到不匹配
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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. 解法： 只要考虑两种情况即可： 第一，如果当前数字是最后一个数字，或者之后的数字比它
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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. 解释： 罗马数字采用七个罗马字母作数字、即Ⅰ（1）、X（10）、C（100）、M（1
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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 '*'. 解法1: 这道题中的*表示*之前的那个字符可以有0个，1个或是多个，就是说，字符串a*b，可以表示b或是aaab，即a的个数任意；字符串.*b，可以表示b或是xyz
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摘要：Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thi
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摘要：Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below
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摘要：Reverse digits of an integer. Example1: Example2: Have you thought about this? Here are some good questions to ask before coding. Bonus points for you
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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. 求字符串中的最大回文子串（从左往右和从右往左读一样的子串）。 Exa
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摘要：关于这三个类在字符串处理中的位置不言而喻，那么他们到底有什么优缺点，到底什么时候该用谁呢？下面我们从以下几点说明一下。 1.三者在执行速度方面的比较：StringBuilder > StringBuffer > String 2.String <（StringBuffer，StringBuilder
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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. Examples: 解法: 建立一个大小为256整形数组，用来记录每个字符上一次出现的位置。longest记录最长的子串长度，
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摘要：You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contai
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摘要：Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have ex
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