Arrays & Hashing

Frequency counting, hash maps, and array manipulation

3 Easy5 Medium0 Hard

All Problems

#	Problem	Pattern	Difficulty
217	Contains Duplicate	Hash Set	Easy
242	Valid Anagram	Frequency Count	Easy
1	Two Sum	Hash Map Lookup	Easy
49	Group Anagrams	Hash Map Grouping	Medium
347	Top K Frequent Elements	Bucket Sort / Heap	Medium
238	Product of Array Except Self	Prefix/Suffix Product	Medium
271	Encode and Decode Strings	Length Prefix Encoding	Medium
128	Longest Consecutive Sequence	Hash Set Sequence	Medium