How should I practice Starting Value with the Longest Collatz Chain?

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

Is Starting Value with the Longest Collatz Chain associated with ZipRecruiter?

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

Starting Value with the Longest Collatz Chain

ZipRecruiter● MediumFULLTIMEPHONE SCREEN

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Problem statement

For a positive value n, repeatedly replace an even value by n / 2 and an odd value by 3n + 1 until reaching 1.

Among starting values from 1 through limit, return the one with the longest chain, counting both the start and 1. Break equal lengths by the smaller starting value.

Function

longestCollatzStart(limit: int) → int

Examples

Example 1

limit = 1return = 1

Only starting value one is available.

Example 2

limit = 2return = 2

Two has a longer chain than one.

Constraints

1 <= limit <= 1000000
Intermediate values fit in signed 64-bit integers.