LeetCode-in-All

287. Find the Duplicate Number

Medium

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 uses 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

Constraints:

Follow up:

Solution

defmodule Solution do
  @spec find_duplicate(nums :: [integer]) :: integer
  def find_duplicate(nums) do
    (nums -- Enum.uniq(nums)) |> hd
  end
end