String Pattern Matching Naive in DSA Python - Build from Scratch

String Pattern Matching Naive

📖 Scenario: You are building a simple search tool that looks for a small word (pattern) inside a bigger text (string). This is like finding a word in a book page by checking each letter one by one.

🎯 Goal: Build a program that finds all starting positions where a given pattern appears in a text using the naive string matching method.

📋 What You'll Learn

Create a variable text with the exact string: 'ababcabcabababd'

Create a variable pattern with the exact string: 'ababd'

Create a list positions to store all starting indices where pattern is found in text

Use a naive approach to check every possible position in text for the pattern

Print the positions list at the end

💡 Why This Matters

🌍 Real World

Searching for words or phrases inside documents, logs, or any text data is a common task in text editors, search engines, and data analysis tools.

💼 Career

Understanding basic string matching helps in roles like software development, data analysis, and quality assurance where text processing is frequent.

1

Create the text and pattern variables

Create a variable called text and set it to the string 'ababcabcabababd'. Also create a variable called pattern and set it to the string 'ababd'.

DSA Python

# Create variables text and pattern with given strings
# Your code here

Hint

Use simple assignment to create text and pattern variables with the exact strings.

2

Create a list to store matching positions

Create an empty list called positions to store the starting indices where the pattern is found in text.

DSA Python

text = 'ababcabcabababd'
pattern = 'ababd'
# Create an empty list positions
# Your code here

Hint

Use [] to create an empty list named positions.

3

Implement naive pattern matching logic

Use a for loop with variable i to check every possible starting index in text where pattern could fit. Inside the loop, use another for loop with variable j to compare characters of pattern with text. If all characters match, append i to positions.

DSA Python

text = 'ababcabcabababd'
pattern = 'ababd'
positions = []
# Use nested loops to find all positions where pattern matches text
# Your code here

Hint

Check each position i in text where pattern can fit. Compare characters one by one. If all match, add i to positions.

4

Print the list of matching positions

Print the positions list to show all starting indices where the pattern was found in text.

DSA Python

text = 'ababcabcabababd'
pattern = 'ababd'
positions = []

for i in range(len(text) - len(pattern) + 1):
    match = True
    for j in range(len(pattern)):
        if text[i + j] != pattern[j]:
            match = False
            break
    if match:
        positions.append(i)

# Print the positions list
# Your code here

Hint

Use print(positions) to show the result.