Find the Duplicate Number

arraytwo pointersbinary search

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.

Example 1

Input: nums = [1,3,4,2,2]
Output: 2

Example 2

Input: nums = [3,1,3,4,2]
Output: 3

Example 3

Input: nums = [3,3,3,3,3]
Output: 3

1 <= n <= 10 ^5

nums.length == n + 1

1 <= nums[i] <= n

All 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?

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicTwo Pointers