Interview Guides

First Unique Element Index

Easy

Basic AlgorithmsloopsData Structures

Problem

Given an array of integers nums, return the index of the first element that appears exactly once in the array. If no such element exists, return -1. The input is a Python list of integers, and the output is a single integer index.

Constraints

1 <= len(nums) <= 10^5
-10^9 <= nums[i] <= 10^9
The solution should run efficiently for large arrays

Problem

Constraints

1 <= len(nums) <= 10^5
-10^9 <= nums[i] <= 10^9
The solution should run efficiently for large arrays

Practice Python

Python 3.10

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

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First Unique Element IndexEasy

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All questions/Coding

First Unique Element Index

Easy

Basic AlgorithmsloopsData Structures

Problem

Constraints

1 <= len(nums) <= 10^5
-10^9 <= nums[i] <= 10^9
The solution should run efficiently for large arrays

Problem

Constraints

1 <= len(nums) <= 10^5
-10^9 <= nums[i] <= 10^9
The solution should run efficiently for large arrays

Practice Python

Python 3.10

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

Up next

First Unique Element IndexEasy

First Duplicate Value IndexEasy

Next question

First Unique Element Index | Dataford Interview Questions