Solution: High-Frequency Bidding

import java.util.concurrent.atomic.AtomicInteger;
public class HighFrequencyBidding {
    static class AuctionItem {
        // 1. Use AtomicInteger for lock-free thread safety
        private AtomicInteger highestBid = new AtomicInteger(0);
        public void submitBid(int bidAmount) {
            while (true) {
                // 2. Read the current state
                int current = highestBid.get();
                // 3. Check logic: Only update if new bid is strictly higher
                if (bidAmount <= current) {
                    return; // Existing bid is already higher or equal; give up.
                }
                // 4. Attempt atomic update (CAS)
                // If current value is still 'current', set it to 'bidAmount'.
                // If success, return true. If fail (value changed), return false.
                if (highestBid.compareAndSet(current, bidAmount)) {
                    // Success! We updated the value.
                    // System.out.println("New High Bid: " + bidAmount); // Optional log
                    return;
                }
                
                // 5. If compareAndSet failed, loop again immediately (Spin Lock)
            }
        }
        public int getHighestBid() {
            return highestBid.get();
        }
    }
    public static void main(String[] args) {
        AuctionItem item = new AuctionItem();
        // 6. Define a heavy workload task
        Runnable bidderTask = () -> {
            for (int i = 0; i < 1000; i++) {
                int randomBid = (int) (Math.random() * 1_000_000);
                item.submitBid(randomBid);
            }
        };
        // 7. Create multiple concurrent threads
        Thread t1 = new Thread(bidderTask);
        Thread t2 = new Thread(bidderTask);
        Thread t3 = new Thread(bidderTask);
        Thread t4 = new Thread(bidderTask);
        Thread t5 = new Thread(bidderTask);
        t1.start(); t2.start(); t3.start(); t4.start(); t5.start();
        try {
            // 8. Wait for everyone to finish
            t1.join(); t2.join(); t3.join(); t4.join(); t5.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Final Highest Bid: " + item.getHighestBid());
    }
}