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Hashing

Lookups, dedup, grouping, frequency, subarray sums.

4 subtopics · 12 problems0/12 on the path solved
next ▸ Contains Duplicatemachine 1000
01

Lookups & dedup

0/7

Two sum, contains duplicate, nearby duplicate.

○Contains DuplicateSilver · 1000○Two SumSilver · 1100○First Unique CharacterSilver · 1150○Intersection of Two ArraysSilver · 1200○Contains Nearby DuplicateSilver · 1200○Intersection With CountsSilver · 1200○Find All DuplicatesGold · 1350
02

Grouping

0/1

Group anagrams, isomorphic, word pattern, sudoku.

○Isomorphic StringsGold · 1400
03

Frequency & top-K

0/2

Top-k frequent, frequency sort.

○Top K Frequent ElementsGold · 1450○Word Frequency CountPlatinum · 1750
04

Subarray sums & sets

0/2

Subarray sum k, longest consecutive, 4-sum count.

○Subarray Sum Equals KGold · 1500○4Sum CountGold · 1500