Update 2018/12/3
(1)Prob 743 Network Delay Time:
use dijkstra method to find shortest path from k to each node, Im not sure whether its an easy problem.
(2)Prob 374 Guess Number Higher or Lower: use [left,right) section when using binary search, then left will be the smallest that satisfy the g(middle)
Update 2018/12/5
(1)Prob 111 Minimum Depth of Binary Tree: Be careful that the input tree is an extremely unbalanced tree; (2)Prob 155 Minimum Stack Use a pair to store the value and the current minimum. Trade off between space and time.