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First Non-Repeating Character

EasyPython00:00
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Welcome to the Python screen.

The question is on your right: First Non-Repeating Character. Read through the requirements first.

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Problem

Given a string s, return the index of the first character that appears exactly once. If no such character exists, return -1.

Constraints

  • 1 <= len(s) <= 10^5
  • s contains lowercase English letters
  • Return -1 if there is no answer
Your solutionPython 3
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