arithmetic

day 1

1. valid-parentheses
2. remove-duplicates-from-sorted-array 双指针
3. merge-sorted-array

day 2

1. maximun-depth-of-binary-tree

day 3

1. add-two-numbers
2. longest-substring-without-repeating-characters
3. longest-palindromic-substring

day 4

1. best-time-to-buy-and-sell-stock;
2. best-time-to-buy-and-sell-stockii;
3. valid-palindrome
4. container-with-most-water

day 5

1. sum-root-to-leaf-numbers
2. single-number **
3. 3-sum

day 6

1. min-stack
2. two-sumii-input-array-is-sorted **
3. factorial-trial-zeroes **

day 7

1. merge-k-sorted-linkedlist 二分法
2. majority-element
3. swap-nodes-in-pairs

day 8

1. reverse-bits ?*****?
2. number-of-1-bits
3. house-robber ***** 动态规划
4. divide-two-intergers

day 9

1. search-rotated-sorted-array ** 二分法
2. combination-sum *** 回溯法
3. remove-linkedlist-element

day 10

1. reverse-linkedlist
2. contains-duplicateii
3. invert-binaryTree

day 11

1. combination-sum-ii

day 12

1. permutations
2. permutations-ii

day 13

1. implement-queue-using-stack
2. ugly-number
3. move-zero

day 14

1. power-of-four
2. intersection-of-two-arrays