First One-Off Letter

Easy

You are given a string text of lowercase English letters. Find the leftmost letter that occurs in the string exactly once and return its index (0-based). If every letter occurs at least twice, return -1.

Example 1

text="teapot" → 1

t occurs twice, while e at index 1 occurs only once.

Example 2

text="abcabd" → 2

a and b repeat; the first letter without a twin is c at index 2.

Example 3

text="xyxy" → -1

Every letter appears twice, so the answer is -1.

Constraints

1 ≤ len(text) ≤ 10⁵
text consists of lowercase English letters

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Topics

Queue Hash Table String Counting

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Input

text="teapot"

Expected

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