Find the Repeated Number in an Array

Implement findDuplicateNumber

You're given an array nums of n + 1 integers, where every value lies between 1 and n. Exactly one value repeats — it might show up more than twice — while every other value appears exactly once. Find and return the repeated value.

Example 1:

Input: nums = [5,2,4,3,1,4]

Output: 4

Example 2:

Input: nums = [3,1,1]

Output: 1

Example 3:

Input: nums = [6,1,2,3,4,5,6]

Output: 6

+ 5 hidden test cases run on Submit.

Constraints:

  • 2 ≤ n ≤ 10⁵, where n + 1 = nums.length
  • 1 ≤ nums[i] ≤ n
  • Exactly one value in nums repeats — it may appear more than twice — and every other value appears exactly once

nums =

[5, 2, 4, 3, 1, 4]