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Grokking the Coding Interview Patterns

Remove Duplicate Letters

Explore how to remove duplicate letters from a string so each letter appears once and the result is lexicographically smallest. Understand using stacks to track characters and practice efficient coding solutions. This lesson helps you build skills important for coding interviews focusing on stack patterns and string manipulation.

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Statement

You are given a string, s, consisting only of lowercase English letters. Your task is to remove duplicate letters so that:

  1. Each letter appears only once in the resulting string.

  2. The resulting string is the smallest in lexicographical order among all possible results that satisfy the above condition.

Return the final string.

A string, a, is considered lexicographically smaller than string b if:

    ...