🧩 Jigsaw Puzzle Builder (Parallel Parts) Concurrency Problem

🧩 The Problem

We’re building a digital jigsaw puzzle game (or simulation) where:

• The puzzle has many pieces (hundreds or thousands).

• Each piece can be placed independently unless it connects to another.

• We want to speed up building the puzzle by letting multiple workers (threads) place pieces at the same time.

Solution Approaches

1️⃣ Step 1 – The Naive Single-Threaded Approach

Imagine we have a jigsaw puzzle with 1,000 pieces.
We write a simple loop:

public class PuzzleBuilder {
    public static void main(String[] args) {
        for (int piece = 1; piece <= 1000; piece++) {
            placePiece(piece);
        }
    }

    static void placePiece(int id) {
        System.out.println("Placed piece " + id);
        try { Thread.sleep(10); } catch (InterruptedException e) {}
    }
}

📝 Idea: One person places all pieces in order.
✅ Works fine for small puzzles.
❌ But slow for large puzzles — only one worker is active.

The Real-World Problem

In real life:

• Multiple people can work on different parts of the puzzle at the same time.

• We don’t need to place pieces in strict numeric order — only in correct locations.

• Our single-thread version wastes potential parallelism.

More Solutions