Find Occurrences Of An Element In An Array · Interview Problem

Back to problems

Leetcode

Medium

Arrays

Hash Maps

Find Occurrences Of An Element In An Array

Return the positions where a target value appears in an array.

Acceptance 0%

Start Practice

Problem Statement

Given an integer array and a target value, find every index at which the target appears. Return the matching indices in increasing order.

This is a straightforward array traversal problem that tests careful iteration and basic frequency/index tracking.

Input Format

An integer array arr
An integer x representing the target value

Output Format

A list of all 0-based indices i such that arr[i] == x
If the target does not appear, return an empty list

Constraints

1 <= arr.length is assumed for practice settings
Elements may be negative, zero, or positive
Return indices in increasing order

Examples

Sample cases returned by the problem API.

Example 1

Input

arr = [1, 2, 3, 2, 4, 2], x = 2

Output

[1, 3, 5]

Explanation

The value 2 appears at indices 1, 3, and 5.

Example 2

Input

arr = [5, 6, 7], x = 1

Output

[]

Explanation

The target value does not occur in the array.

Premium problem context

Unlock deeper context for this problem

Premium adds guided hints, editorial links, similar variants, discussion resources, and concept maps so you can understand why a problem matters, not just solve it once.

Guided hints

Editorial and discussion links

Concept map and variants

Track your progress