Find The Duplicate Number

Given an unsorted array of positive numbers, nums, such that the values lie in the range [1,n], inclusive, and that there are n+1 numbers in the array, find and return the duplicate number present in nums. There is only one repeated number in nums.

Note

You cannot modify the given array nums. You have to solve the problem using only constant extra space.

Constraints

• 1 ≤ n ≤ 10³
• nums.length = n + 1
• 1 ≤ nums[i] ≤ n
• All the integers in nums are unique except for one integer that will appear more than once.