How should I practice Validate a Mahjong Hand Partition?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Duolingo phone screen problems in FastPrep.

Is Validate a Mahjong Hand Partition associated with Duolingo?

FastPrep tags this as a Duolingo phone screen coding practice problem when the problem catalog has that company and stage context.

Duolingo● MediumNEW GRADPHONE SCREEN

A Mahjong-like hand is represented by an unordered array tiles whose values are digits from 1 through 9.

Return whether every tile can be partitioned into:

exactly one pair of equal values (the pair of eyes); and
zero or more three-tile groups, where each group is either three equal values or three consecutive values x, x + 1, x + 2.

Every tile occurrence must belong to exactly one group. The order of tiles in the input does not matter.

isValidMahjongHand(tiles: int[]) → boolean

tiles = [1,1,1,2,3,4,5,6]return = true

Use [1,1] as the pair, then form the runs [1,2,3] and [4,5,6].

tiles = [1,1,1,2,2]return = true

The hand partitions into the triple [1,1,1] and the pair [2,2].

tiles = [1,1,1,1,2]return = false

After choosing any pair, the remaining three tiles form neither a triple nor a consecutive run.