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1. Check Anagram2. Check if Substring Exists3. Count Substring Occurrences4. Extract Numbers from String5. Sum of Numbers in String6. Check if All Characters Same7. Remove Adjacent Duplicates8. Find First Non-Repeating Character9. Find Most Frequent Character10. Check String Rotation11. Longest Common Prefix12. String Compression13. Valid Parentheses Check14. Reverse Words in String

Find First Non-Repeating Character

Find first character that appears only once.

AdvancedPhase 5 - Category 5: Advanced String LogicExample 8 of 14
find-first-non-repeating-character.py
1# Take string input
2s = input("Enter a string: ")
3

4# Find first non-repeating
5freq = {}
6for char in s:
7    freq[char] = freq.get(char, 0) + 1
8

9# Find first with count 1
10result = None
11for char in s:
12    if freq[char] == 1:
13        result = char
14        break
15

16if result:
17    print(f"First non-repeating: {result}")
18else:
19    print("No non-repeating character")

Output

Enter a string: hello
First non-repeating: h

What's going on

Count frequency, then find first with count 1.

Key Concepts:

Count frequency of each character
Find first character with count 1
Return that character

🔗Related Content

PreviousRemove Adjacent DuplicatesNextFind Most Frequent Character