How to Solve Find the Duplicate Number Problem
Master the Find the Duplicate Number LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
Interview Coder generates complete solutions and debugging hints that you can use while explaining your approach, so you stay calm and in control.
Find the Duplicate Number
Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive. There is only one repeated number in nums, return this repeated number. You must solve th...
Interview Coder will help you solve this problem in real-time during your interview
✨ Get instant solutions, explanations, and code generation
Understanding the Find the Duplicate Number Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive. There is only one repeated number in nums, return this repeated number. You must solve the problem without modifying the array nums and using only constant extra space.
Find the Duplicate Number
Related Topics
How Interview Coder Helps
Get real-time assistance for Find the Duplicate Number problems during coding interviews. Interview Coder provides instant solutions and explanations.
Examples
nums = [1,3,4,2,2]2nums = [3,1,3,4,2]3nums = [3,3,3,3,3]3Constraints
1 <= n <= 105nums.length == n + 11 <= nums[i] <= nAll the integers in nums appear only once except for precisely one integer which appears two or more times.Follow up:How can we prove that at least one duplicate number must exist in nums?Can you solve the problem in linear runtime complexity?How Interview Coder Helps with Leetcode Problems
Trust anchors reduce friction for conversion. Reinforce undetectability claims, platform compatibility, user counts, and the free trial to remove perceived risk.
See Interview Coder in Action
Watch how Interview Coder helps solve LeetCode problems during live interviews
Undetectability Checklist
Platform Compatibility
User results and traction
More than 87,000 developers use Interview Coder and early launch metrics showed rapid adoption. Social proof signals that this approach helps real candidates land offers across a range of companies.
Undetectability and technical details
Our native desktop architecture avoids common detection vectors used by browser extensions. We provide a clear checklist so you can run basic checks and confirm the app will be invisible during live interviews.
Platform compatibility and limitations
We work with Zoom, HackerRank, CodeSignal, CoderPad and other web based platforms, with a known list of app version caveats. Check the compatibility note and request a browser link if a specific desktop app is unsupported.
Frequently Asked Questions
Common questions about solving Find the Duplicate Number and using Interview Coder during coding interviews.
Interview Coder generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
Ready to Get Started?
Download Interview Coder now and join thousands of developers who have aced their coding interviews