数组

15.3sum
169.majority element
41.first missing positive

链表

141.linked list cycle
23.merge k sorted list

20.valid parenthess
32.longest valid parentheses
150.evaluate reverse polish notation

641.design circular deque
239.sliding window maxumum

70.climbing stairs

69.sqrt(x)

344.reverse string
151.reverse words in a string
8.string to integer(atoi)

226.invert binary tree
104.maximum depth of binary tree
98.validate binary search tree
112.path sum

200.number of islands
36.vaild sudoku

10.regular expression matching
64.minimum path sum
322.coin change
121.best time to buy and sell stock
152.maximum product subarray
120.triangle