Design ATM Machine

// ========== Cash Slot (Chain Handler) ==========
abstract class CashSlot {
    protected int denomination;
    protected int count;
    protected CashSlot next;
    
    public CashSlot(int denomination, int count) {
        this.denomination = denomination;
        this.count = count;
    }
    
    public void setNext(CashSlot next) {
        this.next = next;
    }
    
    public void dispense(int amount, List<Integer> result) {
        if (amount >= denomination) {
            int notesNeeded = amount / denomination;
            int notesToDispense = Math.min(notesNeeded, count);
            
            if (notesToDispense > 0) {
                result.add(notesToDispense);
                System.out.println("Dispensing " + notesToDispense + " x $" + denomination);
                count -= notesToDispense;
                amount -= notesToDispense * denomination;
            }
        }
        
        if (next != null && amount > 0) {
            next.dispense(amount, result);
        } else if (amount > 0) {
            System.out.println("Cannot dispense remaining: $" + amount);
        }
    }
    
    public boolean canDispense(int amount) {
        int remaining = amount;
        CashSlot current = this;
        
        while (current != null && remaining > 0) {
            int notes = Math.min(remaining / current.denomination, current.count);
            remaining -= notes * current.denomination;
            current = current.next;
        }
        return remaining == 0;
    }
}

class HundredDollarSlot extends CashSlot {
    public HundredDollarSlot(int count) { super(100, count); }
}

class FiftyDollarSlot extends CashSlot {
    public FiftyDollarSlot(int count) { super(50, count); }
}

class TwentyDollarSlot extends CashSlot {
    public TwentyDollarSlot(int count) { super(20, count); }
}

class TenDollarSlot extends CashSlot {
    public TenDollarSlot(int count) { super(10, count); }
}

// ========== Cash Dispenser ==========
class CashDispenser {
    private CashSlot chain;
    
    public CashDispenser() {
        // Build the chain
        CashSlot hundred = new HundredDollarSlot(10);
        CashSlot fifty = new FiftyDollarSlot(20);
        CashSlot twenty = new TwentyDollarSlot(50);
        CashSlot ten = new TenDollarSlot(100);
        
        hundred.setNext(fifty);
        fifty.setNext(twenty);
        twenty.setNext(ten);
        
        this.chain = hundred;
    }
    
    public boolean canDispense(int amount) {
        if (amount % 10 != 0) return false;
        return chain.canDispense(amount);
    }
    
    public List<Integer> dispense(int amount) {
        List<Integer> dispensed = new ArrayList<>();
        if (canDispense(amount)) {
            chain.dispense(amount, dispensed);
        }
        return dispensed;
    }
}

// ========== Usage ==========
public class Main {
    public static void main(String[] args) {
        CashDispenser dispenser = new CashDispenser();
        
        System.out.println("Withdraw $280:");
        dispenser.dispense(280);
        // Output: 2 x $100, 1 x $50, 1 x $20, 1 x $10
        
        System.out.println("\nCan dispense $15? " + dispenser.canDispense(15));
        // Output: false (not multiple of 10)
    }
}