How should I practice Lexicographically Largest Distinct-Letter Subsequence?

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

Is Lexicographically Largest Distinct-Letter Subsequence associated with Navan?

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

Lexicographically Largest Distinct-Letter Subsequence

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Problem statement

Given a lowercase string s, remove characters so that every distinct letter appears exactly once. The remaining characters must preserve their original relative order.

Return the lexicographically largest possible result.

Function

largestUniqueLetters(s: String) → String

Examples

Example 1

s = "bcabc"return = "cab"

The subsequence cab contains each distinct letter once and is lexicographically largest.

Example 2

s = "cbacdcbc"return = "cbad"

Keeping the early c and b allows the largest valid prefix.

Example 3

s = "bbcaac"return = "bca"

The best unique-letter subsequence is bca.

Constraints

1 ≤ s.length ≤ 100000.
s contains only lowercase English letters.