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All questions/Coding/First Non-Repeating Character

First Non-Repeating Character

Easy

Coding

Asked at 1 company1ArraysStringsHash Tables

Also asked at

Problem

Given a string s, return the index of the first character that appears exactly once. If every character repeats, return -1.

Examples

Example 1

Inputs = "leetcode"Output0WhyThe first unique character is `'l'`.

Example 2

Inputs = "aabb"Output-1WhyNo character appears exactly once.

Constraints

`0 <= len(s) <= 10^5`
`s` contains only lowercase English letters
Return `-1` if no unique character exists

Problem

Given a string s, return the index of the first character that appears exactly once. If every character repeats, return -1.

Examples

Example 1

Inputs = "leetcode"Output0WhyThe first unique character is `'l'`.

Example 2

Inputs = "aabb"Output-1WhyNo character appears exactly once.

Constraints

`0 <= len(s) <= 10^5`
`s` contains only lowercase English letters
Return `-1` if no unique character exists

Practice Python

Python 3.10

Open on desktop for the full Python editor with syntax highlighting and autocomplete.

All questions/Coding/First Non-Repeating Character

First Non-Repeating Character

Easy

Coding

Asked at 1 company1ArraysStringsHash Tables

Also asked at

Problem

Given a string s, return the index of the first character that appears exactly once. If every character repeats, return -1.

Examples

Example 1

Inputs = "leetcode"Output0WhyThe first unique character is `'l'`.

Example 2

Inputs = "aabb"Output-1WhyNo character appears exactly once.

Constraints

`0 <= len(s) <= 10^5`
`s` contains only lowercase English letters
Return `-1` if no unique character exists

Problem

Given a string s, return the index of the first character that appears exactly once. If every character repeats, return -1.

Examples

Example 1

Inputs = "leetcode"Output0WhyThe first unique character is `'l'`.

Example 2

Inputs = "aabb"Output-1WhyNo character appears exactly once.

Constraints

`0 <= len(s) <= 10^5`
`s` contains only lowercase English letters
Return `-1` if no unique character exists

Practice Python

Python 3.10

Open on desktop for the full Python editor with syntax highlighting and autocomplete.

First Non-Repeating Character | Dataford Interview Questions - Dataford - Ace your Interview