Pattern Programs in DSA — 22 Patterns

A curated collection of 22 classic pattern-printing programs, commonly asked in coding interviews and an excellent starting point for anyone beginning their Data Structures & Algorithms (DSA) journey.

Pattern problems are one of the best ways to build a strong foundation in loops, nested iteration, and logical thinking — core skills that carry over into more advanced DSA topics like recursion, backtracking, and dynamic programming.

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Why This Repository?

• Beginner-friendly — no prior DSA experience required
• Covers the most frequently asked pattern problems in interviews
• Each pattern includes intuition, approach, and complexity analysis
• Helps build intuition for nested loops and iteration control
• A great warm-up before diving into arrays, strings, and recursion

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Patterns Included

#	Pattern Name	Difficulty
1	Square Pattern	Easy
2	Right-Angled Triangle (Numbers)	Easy
3	Right-Angled Triangle (Stars)	Easy
4	Inverted Right-Angled Triangle	Easy
5	Pyramid Pattern	Easy
6	Inverted Pyramid Pattern	Easy
7	Diamond Pattern	Medium
8	Hollow Square Pattern	Medium
9	Hollow Triangle Pattern	Medium
10	Number Triangle (Increasing)	Easy
11	Number Triangle (Reverse)	Easy
12	Floyd's Triangle	Easy
13	Pascal's Triangle	Medium
14	Butterfly Pattern	Medium
15	Zig-Zag Pattern	Medium
16	Alphabet Triangle	Easy
17	Alphabet Pyramid	Medium
18	Hollow Diamond Pattern	Medium
19	Number Pyramid (Repeated Row Number)	Medium
20	Palindromic Number Pattern	Hard
21	Spiral Number Pattern	Hard
22	Sandglass / Hourglass Pattern	Hard

Update the table above with the exact names/order of your 22 implementations.

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Example Patterns many are there

1. Square Pattern

Intuition: Since the number of rows and columns are equal, two nested loops suffice — the outer loop for rows and the inner loop for printing N stars per row.

Approach:

1. Take an integer N as input to define the size of the square.
2. Use a loop from 0 to N-1 to represent each row.
3. Inside that loop, use another loop from 0 to N-1 to print stars in the current row.
4. Print "* " during each inner loop iteration to form the row.
5. After each inner loop completes, move to the next line.

Complexity:

• Time: O(N²)
• Space: O(1)

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2. Right-Angled Triangle (Numbers)

Intuition: Each row contains numbers starting from 1 up to the row number — row 1 has 1, row 2 has 1 2, row 3 has 1 2 3, and so on until N.

Approach:

1. Use an outer loop i from 1 to N for rows.
2. For each row, use an inner loop j from 1 to i to print numbers.
3. Each row prints numbers starting from 1 up to the current row index.
4. After printing each row, move to the next line.

Complexity:

• Time: O(N²), since the outer loop runs N times and the inner loop runs up to i times for each row.
• Space: O(1), since only loop variables are used.

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Getting Started

# Clone the repository
git clone <your-repo-url>

# Navigate into the project
cd pattern-programs

# Run any pattern file
python patternX.py

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Who Is This For?

This repository is ideal for:

• Students starting their DSA/coding interview prep
• Beginners learning loops and nested iteration
• Anyone who wants daily practice with simple, visual problems before moving to arrays, strings, and recursion

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Contributing

Contributions are welcome! If you'd like to add a new pattern or improve an existing solution:

1. Fork the repository
2. Create a new branch (git checkout -b add-new-pattern)
3. Commit your changes
4. Open a pull request

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License

This project is open-source and available under the MIT License.

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If you found this helpful for your DSA journey, consider giving the repository a star!