In technical interviews, many candidates are asked to implement recursion algorithms using iteration. Generally, an algorithm implemented in iteration will run faster than that in recursion, since it avoids the overhead of function call. With the help of a stack and careful algorithm design, we can convert all recursion algorithms […]
最终去向：Google Software Engineer, New Grad, Mountain View 学校项目：Yale CS MS （一年） 签了Google的offer，withdraw了Bloomberg和Oracle的面试，算是结束了自己的求职之路。激动是有的，因为二十多年来，终于实现了经济独立。 但也有些失落，因为其他的可能性都随之崩塌。近期都不会再碰算法题了，Leetcode的解题记录也停在了308。写下这篇文章，总结求职中的经验和教训，也希望帮到后来人。 图：Shu Tao 白岩松说，永远不要相信老人写的回忆录，因为他们会选择性地回忆过去，只留下筛选后的内容。于是他们的人生轨迹与抉择看起来是那么的顺理成章。我会尽量客观地写这一年来我做的事情，中间有些许经验，也有不少教训。 选择学校 申请学校时我就决定毕业后找工作。出于经济考虑，自己最终从CMU MIIS，Cornell Meng和Yale CS中选择了后者。每当自己在朋友圈或是Facebook上看到CMU的同学凌晨三点发的写代码的状态，就会感慨这可能是自己差一点选择的生活。感慨过后，自己就又去继续思考晚上到底是炖鸡还是炖牛肉的哲学问题去了。 耶鲁的课程对找工作的帮助微乎其微，我想大部分学校的课程都是这样。因为课程目的就不是为了帮助学生找工作，而是训练学生理解计算机原理，甚至是独立思考，和面对未来生活的能力。当然也有学校诸如MIT就开设了Hacking a Google Interview这样的神课，那就是另外一个故事了。不过，耶鲁计算机系的教授单拎出来都是各个领域的神牛。比如Avi Silberschatz，你可能没听过他的名字，但你一定用过他的教材。 此外，在耶鲁读书，还会给你机会认识一群优秀的同学。 练习白板 图：Bo Song 刷题的环境很重要，尤其是能和一群优秀的人一起准备面试。头脑风暴之后，我们往往能把算法复杂度降低一个量级。这种感觉有点像高三复习备战高考，整间教室的人都朝着同一个目标努力。曾和另一位拿了Yale和Cornell Offer，同样纠结去哪家的同学聊天，她觉得刷题的环境和校友资源是选择学校的考量。我表示认同。因为你的水平取决于你周围人水平的平均值，这种影响是潜移默化的。 我本科的一位同学（浙大），本科毕业前就收到了谷歌的offer，同时一位杭州IT公司的老板也极力挽留他。后者开出的价码很诱人，“谷歌给你什么，我就给你什么。并且直接让你领导一个团队。”这位同学讲，最后一个条件对他的诱惑力很大，但转念一想团队里那些人的水平，最终还是选择去谷歌。“很希望与一群优秀的人共事，会让自己也不断进步。”他说。 很有幸能在耶鲁认识这么多优秀的同学，感谢他们带给我的积极影响。我可能是找工作找得最快的一个，但绝对不会是找得最好的一个。祝愿大家都能拿到理想的offer。学校项目可以改变人的气质，我们也可以改造Yale CS MS的形象。 Yale CS MS 2015 Fall 部分同学 图：Aohan Lin 准备面试 我开始刷题(Leetcode)是在2015年1月份，也就是大四下学期，那时刚准备完申请。这里还保存着我Leetcode上AC的第一道题的题解：http://www.sunny-song.com/best-time-to-buy-and-sell-stock/ 如果按照时间顺序从旧到新地看的话，可以一览我的代码从稚嫩笨拙(too young too simple)到还算整洁规范(neat and clean)的成长过程。 […]
Range Sum Query 2D – Mutable Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and […]
Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by updating the element at index i to val. Example: Given nums = [1, 3, 5] sumRange(0, 2) -> 9 update(1, 2) sumRange(0, 2) […]
Topological Sorting Medium Topological SortingShow result 25% Accepted Given an directed graph, a topological order of the graph nodes is defined as follow: For each directed edge A -> B in graph, A must before B in the order list. The first node in the order can be any node […]
Additive number is a positive integer whose digits can form additive sequence. A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the preceding two. For example: “112358” is an additive number because […]
Isomorphic Strings Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map […]
Implement Queue using Stacks Implement the following operations of a queue using stacks. push(x) — Push element x to the back of queue. pop() — Removes the element from in front of queue. peek() — Get the front element. empty() — Return whether the queue is empty. Notes: You must […]
Kth Largest Element in an Array Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. For example, Given [3,2,1,5,6,4] and k = 2, return 5. Note: You may assume k is always valid, […]
Flatten Binary Tree to Linked List Flatten a binary tree to a fake “linked list” in pre-order traversal. Here we use the right pointer in TreeNode as the nextpointer in ListNode. Have you met this question in a real interview? Yes Example 1 \ 1 2 / \ \ 2 […]
