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 exactly one repeated number in nums. Return this repeated number.

You must solve the problem without modifying the array and uses only constant extra space.

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Example 1

Input: nums = [1, 3, 4, 2, 2]
Output: 2
Explanation: The number 2 appears twice.

Example 2

Input: nums = [3, 1, 3, 4, 2]
Output: 3
Explanation: The number 3 appears twice.

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Constraints

• 1 <= n <= 10^5
• nums.length == n + 1
• 1 <= nums[i] <= n
• There is only one repeated number in nums, but it could be repeated more than twice.