Find the Duplicate Number

Question

com

Given an array of integers, find the single duplicate number in the array and return its value.

Example 1

Input: [2, 3, 1, 5, 4, 3]
Output: 3

Solution

▭

all//Find the Duplicate Number.py

def find_duplicate_number(arr):
  seen = set()
  for num in arr:
    if num in seen:
      return num
    else:
      seen.add(num)
  return -1

▯

all//Find the Duplicate Number.py

def find_duplicate_number(arr):
  seen = set()
  for num in arr:
    if num in seen:
      return num
    else:
      seen.add(num)
  return -1