First Non-Repeating Character 🎯

Welcome to today's lesson, where we'll explore an interesting problem-solving approach called the "First Non-Repeating Character"! This concept is essential for beginners and intermediates alike, as it helps you understand data structures and algorithms better. Let's dive in!

Understanding the Problem 📝

Given a string, find the first non-repeating character in it. If no non-repeating character exists, return an empty string.

For example, for the string "abbacbb", the first non-repeating character is "a".

Breaking Down the Solution 💡

To solve this problem, we'll create a hash table (also known as a dictionary or map) to store the characters in the string and their respective counts. After that, we'll iterate through the string and check for characters with count 1 (i.e., non-repeating characters).

Python Solution ✅

Here's a Python implementation:

python

def first_non_repeating(s):
    char_count = {}

    for char in s:
        if char in char_count:
            char_count[char] += 1
        else:
            char_count[char] = 1

    for char, count in char_count.items():
        if count == 1:
            return char

    return ""  # No non-repeating characters found

In the code above, we first initialize an empty dictionary char_count. Then, we iterate through the string s and update the dictionary with the count of each character. After that, we iterate again and return the first character with a count of 1. If no such character is found, we return an empty string.

Quiz Time 💡

Stay tuned for more lessons on Data Structures and Algorithms! 🚀💻