Lc873.length of longest fibonacci subsequence

back_trakcing   and recurrsive

dynamic programming:得到一个递归表达式

36：29 dp做法

作业：Lc1414. find the minimum number of fibonacci numbers whose sum is k

recursion 在 merging two sorted list里面怎么用。lc21

Lc82 removeduplicates from sorted list II  10min.  在53min处用递归，

Lc 658 Find K closet elements.可以一用heapsort，，

Lc 347 top K frequent element;

• quick select

Lc215   kth element in an array  可以用heap。也可以quick select

Lc973 k closet points to origin

LC56  merge interval  例题讲解， stack是啥啊，要先sort

Lc1288 remove covered intervals例题1：30min

lc252 meeting room 1h40min处例题