按类型，从Easy到Hard。
使用javascript。
- 1. Two Sum
- 26. Remove Duplicates from Sorted Array
- 27. Remove Element
- 66. Plus One
- 88. Merge Sorted Array
- 118. Pascal's Triangle
- 119. Pascal's Triangle II
- 121. Best Time to Buy and Sell Stock
- 169. Majority Element
- 189. Rotate Array
- 217. Contains Duplicate
- 219. Contains Duplicate II
- 228. Summary Ranges
- 283. Move Zeroes