在职刷题打卡，目标工作日一天2题，周末一天5题

今日主刷图：
graph clone dfs
union find几道题，无向图上union find可以用来 （1）查看是否有环 （2）数有几个connected component
Network DelayTime:
复习了dijisktra 算法，终于算是比较清楚的明白了它和普通dfs/bfs + keep track of current smallest dist的区别
都是用来求带权重有向图上离某点最短距离的

141, 142, 202, 287
一会看看还有没有空做点别的tag

上周因为工作原因一共刷了三道题，惭愧，希望这周能多刷

#Day_13

完成 * 2:
LC 364. Nested List Weight Sum II
LC 6. ZigZag Conversion

Word Square (DFS + trie tree) and Clone Graph (bfs).

It seems like that most word hard problem could use trie tree to optimize.

252. Meeting Rooms
56. Merge Intervals

Day2:
787. Cheapest Flights Within K Stops
743. Network Delay Time

#Day_14

完成 * 2:
LC 51. N-Queens
LC 426. Convert Binary Search Tree to Sorted Doubly Linked List

Day 2
BFS,
LintCode shortest path in undirected graph, six degrees and search graph node => straightforward bfs, nothing fancy
word ladder I, get the shortest distance from one string to another, the trick is how to traverse. Traverse by changing each character of the string, and see if the dict contains the new string.

136. Single Number
253. Meeting Rooms II 两种方法写了这题