First unique character
Difficulty: Easy
Return the index of the first character occurring exactly once, or -1 if there is none.
Examples
'swiss'1'aabb'-1''-1Constraints
0–10,000 code points. Indices are zero-based.
Review lesson: Frequency mapsA little nudge
Reveal one hint at a time. Give yourself a moment to try it.
Worked solution
Try your own approach first, then compare the reasoning.
Complexity
Ready when you are
Write your solution, then run it against the practice tests.
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