Ethan Li 的技术专栏

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[Leetcode] Max Area of Island 最大岛屿面积

ethannnli 2019-02-01 发布
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Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are sur...

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[Leetcode] Cheapest Flights Within K Stops K次转机最便宜机票

ethannnli 2019-01-24 发布
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There are n cities connected by m flights. Each fight starts from city u and arrives at v with a price w.Now given all the cities and flights, together with starting city src and the destination ds...

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[Leetcode] Evaluate Division 计算除法

ethannnli 2018-12-05 发布
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Equations are given in the format A / B = k, where A and B are variables represented as strings, and k is a real number (floating point number). Given some queries, return the answers. If the answe...

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[Leetcode] Bus Routes 公交线路

ethannnli 2018-11-06 发布
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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 the first bus (0-th indexed) travels in the seq...

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[Leetcode] Self Dividing Numbers 自除数

ethannnli 2018-10-23 发布
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A self-dividing number is a number that is divisible by every digit itcontains.For example, 128 is a self-dividing number because 128 % 1 == 0, 128 % 2 == 0, and 128 % 8 == 0. Also, a self-dividing...

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[Javascript] 实现setInterval函数

ethannnli 2018-04-01 发布
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经常使用Javascript的同学一定对setInterval非常熟悉，当使用setInterval(callback, timer)时，每经过timer毫秒时间，系统都将调用一次callback。请问全局如果没有提供setInterval函数，该如何自己实现这一功能？

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[Leetcode] Cheapest Flights Within K Stops 计算最便宜票价

ethannnli 2018-02-24 发布
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There are n cities connected by m flights. Each fight starts from city u and arrives at v with a price w.Now given all the cities and fights, together with starting city src and the destination dst...

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[Leetcode] Matchsticks to Square 火柴拼方形

ethannnli 2018-02-21 发布
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Remember the story of Little Match Girl? By now, you know exactly whatmatchsticks the little match girl has, please find out a way you canmake one square by using up all those matchsticks. You shou...

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[Leetcode] Repeated Substring Pattern 重复子串格式

ethannnli 2018-02-20 发布
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Given a non-empty string check if it can be constructed by taking asubstring of it and appending multiple copies of the substringtogether. You may assume the given string consists of lowercaseEngli...

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[Leetcode] Unique Substrings in Wraparound String 循环字符串中的唯一子串

ethannnli 2018-02-20 发布
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Consider the string s to be the infinite wraparound string of"abcdefghijklmnopqrstuvwxyz", so s will look like this:"...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....".Now we have an...

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[Algo] Constant Time Random Picker 获取集合内随机元素

ethannnli 2015-11-08 发布
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要求O(1)时间查询和删除，则想到哈希表，其他的数据结构都要遍历一遍才行。但是getRandom这功能有要求我们必须保持内容的有序，这样我们才能通过随机数的方法得到随机的某个元素。这里我们可以用数组、链表或者树...

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[Leetcode] Binary Tree Longest Consecutive Sequence 二叉搜索树最长序列

ethannnli 2015-11-06 发布
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Given a binary tree, find the length of the longest consecutive sequence path. The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connec...

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[Algo] Maximum Expression Value 表达式最大值

ethannnli 2015-11-02 发布
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给定一个整数数组，要求在数字之间任意添加乘号，加号和括号，使得最后表达式结果最大。比如1121,最大值为(1+1)*(2+1)，所有数字都是正数。

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[Algo] Parse XML Tree 解析XML文件

ethannnli 2015-11-01 发布
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现在有一个Tokenizer，返回的Token都是XML标签或者内容，比如(open, html)(inner, hello)(close, html)表示<html>hello</html>，每一个括号及其内容是一个Token，请问如何表示这个XML文件。

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[Algo] Install Dependencies 安装依赖

ethannnli 2015-10-29 发布
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给定软件之间安装的依赖关系，用一个二维数组表示，第一维表示依赖的序号，第二维表示依赖关系，比如要先装deps[0][0]，才能装deps[0][1]。安装时，要尽可能先安装依赖个数少的软件。求安装顺序。

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[Leetcode] Repeated DNA Sequences 重复DNA序列

ethannnli 2015-10-29 发布
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All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA. Wri...

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[Leetcode] Minimum Size Subarray Sum 最短子串和

ethannnli 2015-10-29 发布
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Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead. For example, given the array [2,3,1...

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[Leetcode] Walls and Gates 墙与门

ethannnli 2015-10-26 发布
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You are given a m x n 2D grid initialized with these three possible values. -1 - A wall or an obstacle. 0 - A gate. INF - Infinity means an empty room. We use the value 231 - 1 = 2147483647 to repr...

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[Leetcode] Shortest Word Distance 最短单词间距

ethannnli 2015-10-26 发布
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Given a list of words and two words word1 and word2, return the shortest distance between these two words in the list. For example, Assume that words = ["practice", "makes", "perfect", "coding", "m...

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[Leetcode] One Edit Distance 编辑距离为一

ethannnli 2015-10-26 发布
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Given two strings S and T, determine if they are both one edit distance apart.