Problem 8 ZeroEvenOdd Multithreading Problem

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class Solution {

  // Declare instance variables that are essential for our solution
  private int n; // The number up to which we need to print
  private int counter = 1; // Counter to keep track of the current number being printed

  // Use ReentrantLock for synchronization as it's more flexible than synchronized methods or blocks
  private final Lock lock = new ReentrantLock();

  // Conditions are used to coordinate threads. Here, we declare three conditions:
  // one for zeros, one for even numbers, and one for odd numbers
  private final Condition zeroCondition = lock.newCondition();
  private final Condition evenCondition = lock.newCondition();
  private final Condition oddCondition = lock.newCondition();

  // Flags to keep track of whose turn it is to print
  private boolean zeroTurn = true; // We start with zero
  private boolean oddTurn = true; // We start with odd after zero, before even

  // Constructor: Initializes the object and sets the value of n
  public Solution(int n) {
    this.n = n;
  }

  // Method for thread A to print zeros
  public void zero() throws InterruptedException {
    for (int i = 0; i < n; i++) {
      lock.lock(); // Acquire the lock before checking conditions and printing
      try {
        // Keep the thread in a waiting state while it's not zero's turn to print
        while (!zeroTurn) {
          zeroCondition.await();
        }

        printNumber(0); // Once out of the wait state, print zero

        zeroTurn = false; // Switch the flag since zero has been printed

        // Depending on whether the next number is odd or even, signal the appropriate thread to take over
        if (oddTurn) {
          oddCondition.signal();
        } else {
          evenCondition.signal();
        }
      } finally {
        lock.unlock(); // Always release the lock in the finally block to ensure it's released under all circumstances
      }
    }
  }

  // Method for thread B to print even numbers
  public void even() throws InterruptedException {
    for (int i = 2; i <= n; i += 2) {
      lock.lock();
      try {
        // The even thread waits if it's zero's turn to print or if the current number is odd
        while (zeroTurn || oddTurn) {
          evenCondition.await();
        }

        printNumber(i); // Print the even number

        zeroTurn = true; // Switch the turn back to zero
        oddTurn = true; // After an even, the next number will be odd

        zeroCondition.signal(); // Signal the zero thread to take over
      } finally {
        lock.unlock();
      }
    }
  }

  // Method for thread C to print odd numbers
  public void odd() throws InterruptedException {
    for (int i = 1; i <= n; i += 2) {
      lock.lock();
      try {
        // The odd thread waits if it's zero's turn or if the current number is even
        while (zeroTurn || !oddTurn) {
          oddCondition.await();
        }

        printNumber(i); // Print the odd number

        zeroTurn = true; // Switch the turn back to zero
        oddTurn = false; // After an odd, the next number will be even

        zeroCondition.signal(); // Signal the zero thread to take over
      } finally {
        lock.unlock();
      }
    }
  }

  // Utility method to actually output the number to the console
  public void printNumber(int num) {
    System.out.print(num);
  }

  // Main method to demonstrate the solution
  public static void main(String[] args) {
    // Create an instance of the ZeroEvenOdd class with a value of 5
    Solution zeo = new Solution(5);

    // Create three threads: one for zero, one for even numbers, and one for odd numbers
    Thread t1 = new Thread(() -> {
      try {
        zeo.zero();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    });

    Thread t2 = new Thread(() -> {
      try {
        zeo.even();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    });

    Thread t3 = new Thread(() -> {
      try {
        zeo.odd();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    });

    // Start all the threads
    t1.start();
    t2.start();
    t3.start();
  }
}

I'm working on the problem **Problem 8 ZeroEvenOdd Multithreading Problem** (Concurrency). Give me a HINT LADDER: start with the tiniest nudge, then wait. Only reveal the next, stronger hint when I ask. Do NOT show the full solution unless I type 'show solution'. Keep me doing the thinking. If you're unsure or a claim isn't standard, say so and reason from first principles instead of guessing.

Explain the optimal approach to **Problem 8 ZeroEvenOdd Multithreading Problem** with a VISUAL walkthrough: trace it on a small concrete example using ASCII art / a step-by-step diagram, narrate what changes each step, then give time & space complexity with a one-line derivation. If you're unsure or a claim isn't standard, say so and reason from first principles instead of guessing.

I'll paste my solution to **Problem 8 ZeroEvenOdd Multithreading Problem**. Review it for correctness, missed edge cases, and time/space complexity, then coach me toward the optimal — don't just rewrite it. Ask me to paste my code now. If you're unsure or a claim isn't standard, say so and reason from first principles instead of guessing.

Give me 2 problems that use the SAME underlying pattern as **Problem 8 ZeroEvenOdd Multithreading Problem**. For each, let me attempt first, then review my answer and name the trigger signal that reveals the pattern. If you're unsure or a claim isn't standard, say so and reason from first principles instead of guessing.