最近常聽的一首歌～～超洗腦, 讓人想去波多黎各了～ Despacito
Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. Note: Given target value is a floating point. You are guaranteed to have only one unique value in the BST that is closest to the target.
Given an interval list which are flying and landing time of the flight. How many airplanes are on the sky at most?
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving onlydistinct numbers from the original list.
Given a sorted linked list, delete all duplicates such that each element appear only once.
Remove all elements from a linked list of integers that have value?val.