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Python BasicsEasy
Finding Repeating elements in an Array
Learn how to solve the 'Finding Repeating elements in an Array' problem. This detailed resource details brute force and optimized approaches.
Problem Statement
Easy
Write a function find_repeating(arr) that takes a list of integers arr and returns a sorted list of all elements that appear more than once in the array. If no element repeats, return an empty list.
Constraints
- •0 <= len(arr) <= 10^5
- •-10^6 <= arr[i] <= 10^6
Examples
Example 1
Input
arr = [1, 2, 3, 2, 4, 3]
Output
[2, 3]
Explanation
2 appears twice and 3 appears twice. Both are repeating elements.
Example 2
Input
arr = [1, 2, 3, 4]
Output
[]
Explanation
All elements appear exactly once. No repeating elements.
Example 3
Input
arr = [5, 5, 5, 5]
Output
[5]
Explanation
5 repeats (appears 4 times).
Need a Hint?
Use simple arithmetic operators (like modulo `%`, division `//`), conditional checks, or loops to inspect number properties.
Edge Cases to Watch
- Empty list or null input variables
- Single item lists/arrays
- Extremely large input bounds causing integer or stack overflow
Ready to Solve?
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