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We are given a personal information string S, which may represent either an email address or a phone number. We would like to mask this personal infor 阅读全文
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In a string S of lowercase letters, these letters form consecutive groups of the same character. For example, a string like S = "abbxxxxzyy" has the g 阅读全文
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Given a set of N people (numbered 1, 2, ..., N), we would like to split everyone into two groups of any size. Each person may dislike some other peopl 阅读全文
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The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding one 阅读全文
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We have a list of bus routes. Each routes[i] is a bus route that the i-th bus repeats forever. For example if routes[0] = [1, 5, 7], this means that t 阅读全文
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In a given integer array A, we must move every element of A to either list B or list C. (B and C initially start empty.) Return true if and only if af 阅读全文
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We have jobs: difficulty[i] is the difficulty of the ith job, and profit[i] is the profit of the ith job. Now we have some workers. worker[i] is the a 阅读全文
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Some people will make friend requests. The list of their ages is given and ages[i] is the age of the ith person. Person A will NOT friend request pers 阅读全文
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A sentence S is given, composed of words separated by spaces. Each word consists of lowercase and uppercase letters only. We would like to convert the 阅读全文
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Given an array of unique integers, each integer is strictly greater than 1. We make a binary tree using these integers and each number may be used for 阅读全文
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On a table are N cards, with a positive integer printed on the front and back of each card (possibly different). We flip any number of cards, and afte 阅读全文
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After install the Nginx on AWS instance, and visit your public ip address, you might see the following: This site can't be reached xxx.xxx.xx take too 阅读全文
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Given a string S and a character C, return an array of integers representing the shortest distance from the character C in the string. Example 1: Inpu 阅读全文
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Given a list of words, we may encode it by writing a reference string S and a list of indexes A. For example, if the list of words is ["time", "me", " 阅读全文
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Given a paragraph and a list of banned words, return the most frequent word that is not in the list of banned words. It is guaranteed there is at leas 阅读全文
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使用MongoDB的时候，如果遇到下面这个错误： 一般来说是MongoDB数据库的Model没有链上，在YourScript.js的开头，一般下面几行不能少： 然后yourModel.js的内容可以为： 阅读全文
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Go to Elastic Beanstalk -> Configuration -> Security -> Virtual machine permissions -> EC2 key pair. Choose your key pair. If you do not have one, The 阅读全文
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当你想给微信公众号（不是测试账号）自定义菜单创建接口，遇到如下错误： 很可能的原因是你并没有自定义菜单接口的权限，去【开发】->【接口权限】 界面去查看“自定义菜单”的权限，如果显示 “未获得”，那么恭喜你，用不了。而显示的获得条件是【1】订阅号必须通过微信认证 【2】服务号自动获得。但是坑爹的是， 阅读全文
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Given a blacklist B containing unique integers from [0, N), write a function to return a uniform random integer from [0, N) which is NOT in B. Optimiz 阅读全文
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When install the yeoman using the following command: You might have the following error: Try the following commands instead: Now try to type 'yo' to s 阅读全文
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Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase. Example 1: Input: "Hello" Output: "hello" 阅读全文
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在使用微信官方给的添加自定义菜单的示例代码： 可能会遇到如下的错误： 原因可能是因为想展示的按钮太多了，装不下了，去掉最后两个就好了： 阅读全文
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Design your implementation of the linked list. You can choose to use the singly linked list or the doubly linked list. A node in a singly linked list 阅读全文
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Given a robot cleaner in a room modeled as a grid. Each cell in the grid can be empty or blocked. The robot cleaner with 4 given APIs can move forward 阅读全文
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When the 'fatal error: helper_math.h: No such file or directory' occurs, it means the 'helper_math.h' file is missing. In fact, 'helper_math.h' locate 阅读全文
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Given a node from a Circular Linked List which is sorted in ascending order, write a function to insert a value insertVal into the list such that it r 阅读全文
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Design a HashMap without using any built-in hash table libraries. Implement the MyHashMap class: MyHashMap() initializes the object with an empty map. 阅读全文
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Design a HashSet without using any built-in hash table libraries. To be specific, your design should include these functions: add(value): Insert a val 阅读全文
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Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or 阅读全文
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Design an algorithm to encode an N-ary tree into a binary tree and decode the binary tree to get the original N-ary tree. An N-ary tree is a rooted tr 阅读全文
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Design a class to find the kth largest element in a stream. Note that it is the kth largest element in the sorted order, not the kth distinct element. 阅读全文
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Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, 阅读全文
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Given an integer array sorted in ascending order, write a function to search target in nums. If target exists, then return its index, otherwise return 阅读全文
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Given the root node of a binary search tree (BST) and a value to be inserted into the tree, insert the value into the BST. Return the root node of the 阅读全文
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Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node's value equals the given value. Retu 阅读全文
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Design your implementation of the circular double-ended queue (deque). Your implementation should support following operations: MyCircularDeque(k): Co 阅读全文
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Design your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (F 阅读全文
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Given an n-ary tree, return the preorder traversal of its nodes' values. For example, given a 3-ary tree: Return its preorder traversal as: [1,3,5,6,2 阅读全文
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Given an n-ary tree, return the postorder traversal of its nodes' values. For example, given a 3-ary tree: Return its postorder traversal as: [5,6,3,2 阅读全文
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Given a n-ary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest le 阅读全文
