Finding the First Duplicate in an Array

Introduction

This tutorial will guide you through creating an algorithm to find the first duplicate in an array of numbers.

Step 1: Define the Problem

We are given an array of numbers and we need to find the first duplicate in the array.

Step 2: Initialize an Empty Set

We will initialize an empty set to store the numbers we have seen so far.

Step 3: Iterate Through the Array

We will iterate through the array and check if each number is in the set.

Step 4: Return the First Duplicate

If we find a number that is already in the set, we will return it as the first duplicate.

Example Code

def find_first_duplicate(array):
    seen = set()
    for num in array:
        if num in seen:
            return num
        seen.add(num)
    return None
print(find_first_duplicate([2, 1, 3, 4, 2]))  # Output: 2

Conclusion

In this tutorial, we learned how to write an algorithm to find the first duplicate in an array of numbers.