# 哈希(Hash)

### 练习  
* [Letter count](LetterCount.java)
* [First Character in a String](FirstCharacter.java)
* [Intersection of Two Arrays I](IntersectionOfTwoArrays.java)
* Intersection of Two Arrays II
* Jewels and Stones
* Contains Duplicates
* [Contains Duplicates II](ContainsDuplicatesII.java)
* [Contains Duplicates III](ContainsDuplicatesIII.java)
* Subdomain visit count
* Keyboard Row
* Word Pattern