How should I practice Restore Addresses with K Segments?

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

Is Restore Addresses with K Segments associated with ByteDance?

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

Problem · String

Restore Addresses with K Segments

Learn this problem

● Medium

ByteDanceFULLTIMEPHONE SCREEN

Problem statement

You are given a string digits containing only decimal digits and an integer segmentCount.

Insert exactly segmentCount - 1 dots so that every resulting segment:

contains between one and three digits,
represents an integer from 0 through 255, and
has no leading zero unless the segment is exactly 0.

Return every valid dotted address in lexicographic order. Return an empty array when no valid address exists.

When segmentCount = 4, this is the standard restoration rule for IPv4 addresses; other values use the same segment rules.

Function

restoreAddresses(digits: String, segmentCount: int) → String[]

Examples

Example 1

digits = "25525511135"segmentCount = 4return = ["255.255.11.135","255.255.111.35"]

Both outputs have four valid segments, and no other placement satisfies the value and leading-zero rules.

Example 2

digits = "010010"segmentCount = 4return = ["0.10.0.10","0.100.1.0"]

A segment beginning with 0 must be exactly 0, which eliminates placements such as 01.

Example 3

digits = "1234"segmentCount = 2return = ["1.234","12.34","123.4"]

With two segments, the dot may follow the first, second, or third digit, and every resulting segment remains at most 255.

Constraints

1 ≤ digits.length ≤ 30.
digits contains only decimal digits.
1 ≤ segmentCount ≤ 10.
The total number of returned characters fits in memory.