CodingMediumcod-g574

Subject Two pointersLevel Mid–Senior~24 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given an array nums of n+1 integers where every value is in the range [1, n], exactly one value is duplicated (possibly multiple times). Return that duplicated value without modifying the array and using only O(1) extra space. Array length up to 1e5.

Implement

find_duplicate(nums: list[int]) → int

Examples

in[[1,3,4,2,2]]out2

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.