弱鸡刷题打卡贴

973. K Closest Points to Origin

练习用heapq library

937. Reorder Log Files
耐心读题

811. Subdomain Visit Count

205. Isomorphic Strings
char双向检查

20. Valid Parentheses

12/10

112. Path Sum

12/11

155. Min Stack

7. Rotate Array

236. Lowest Common Ancestor of a Binary Tree

268. Missing Number

111. Minimum Depth of Binary Tree
DFS

111. Minimum Depth of Binary Tree
BFS. 此题用BFS的优点在于由于是按level(depth)遍历，如果当前pop出来的node的depth已经大于目前的minDepth，直接结束战斗

199. Binary Tree Right Side View
BFS同时用一个map来记录每个level

559. Maximum Depth of N-ary Tree

BFS 并且keep一个globalMax的var. DFS的recursive做法比BFS慢。