Duplicate element

Question

Duplicate element You are given an array arr of size n that contains elements from 1 to n-1, where one of the elements appears twice in the array. Write a function to find and return this number. Example 1 > - **Input:** arr = [1, 4, 3, 2, 2] > - **Output:** 2 > - **Explanation:** The element that appears twice is 2. Example 2 > - **Input:** arr = [4, 1, 5, 3, 2, 5] > - **Output:** 5 > - **Explanation:** The element that appears twice is 5. Example 3 > - **Input:** arr = [1, 1] > - **Output:** 1 > - **Explanation:** The element that appears twice is 1.

Accepted Answer

Optimal Solution: Time Complexity O(N), Space Complexity O(1). Codeintuition provides an interactive coding environment for this problem.