How should I practice Maximum Valid Substring Frequency?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Roblox online assessment problems in FastPrep.

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FastPrep tags this as a Roblox online assessment coding practice problem when the problem catalog has that company and stage context.

Maximum Valid Substring Frequency

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Problem statement

A valid substring of s is contiguous, has length from minLength through maxLength inclusive, and contains at most maxUnique distinct letters.

For this exercise, assume occurrences at different starting positions are counted separately, including overlapping occurrences. Return the largest occurrence count of any one valid substring value. Return 0 if no substring is valid. The result is a count, so no tie rule between equally frequent substring values is needed.

Function

maxSubstringFrequency(s: String, minLength: int, maxLength: int, maxUnique: int) → int

Examples

Example 1

s = "aaaaa"minLength = 2maxLength = 3maxUnique = 1return = 4

aa occurs at four starting positions, including overlaps. aaa occurs three times, so the answer is 4.

Example 2

s = "aabcabcaab"minLength = 3maxLength = 5maxUnique = 2return = 2

aab occurs twice and uses only two distinct letters. It is a valid substring with the greatest frequency.

Example 3

s = "abc"minLength = 2maxLength = 2maxUnique = 1return = 0

Both length-2 substrings contain two distinct letters and exceed the limit 1.

Constraints

1 <= s.length <= 10000; s contains lowercase English letters.
1 <= minLength <= maxLength <= min(26, s.length).
1 <= maxUnique <= 26.