linkedin

[gewhiz]

singleton并让其thread-safe，还问到了lazy initialiation的和volatile关键字的意义

[gewhiz]

binary tree level order traversal, 写了三种方法。。。(BFS用arraylist，类似 DFS，BFS用queue)

onsite:

1. romanToInt, intToRoman, N points, m nearst ones
2. 双向链表，每个node可能都有父节点和子节点，每个父子节点又是一个链表。把它 拍扁，顺序随意，O(1)空间复杂度 edit distance
3. system deisign: design amazon product page
4. project presentation
5. group fit

[gewhiz]

http://www.geeksforgeeks.org/given-an-array-of-of-size-n-finds-all-the-elements-that-appear-more-than-nk-times/

[gewhiz]

hashmap，写完后继续要求要考虑multi-thread

linkedin 有两类用户，普通user和influencer，数据量都很大，写一个类， 要求O(1)的 get(user), set(user, type), getAllInfluencer. 我一开始用两个 hashset，问我有没更好的办法，后来问明白他其实就是想要bitset， 写出搞定

[gewhiz]

http://leetcode.com/2010/09/serializationdeserialization-of-binary.html

[gewhiz]

minimize the cost of painting K houses, each house has different costs to paint in different colors, 2 houses (next to each other) cannot be painted in the same color. DP

http://stackoverflow.com/questions/24646122/3-houses-and-minimum-cost-of-painting