Bridge in Java

class Node {

    public int  value;

    public Node prev, next;

    public Node( int i ) { value = i; }

}

 

class StackArray {

    private int[] items = new int[12];

    private int   total = -1;

    public void push( int i ) { if ( ! isFull()) items[++total] = i; }

    public boolean isEmpty()  { return total == -1; }

    public boolean isFull()   { return total == 11; }

    public int top() {

        if (isEmpty()) return -1;

        return items[total];

    }

    public int pop() {

        if (isEmpty()) return -1;

        return items[total--];

}   }

 

class StackList {

    private Node last;

    public void push( int i ) {

        if (last == null)

            last = new Node( i );

        else {

            last.next = new Node( i );

            last.next.prev = last;

            last = last.next;

    }   }

    public boolean isEmpty() { return last == null; }

    public boolean isFull()  { return false; }

    public int top() {

        if (isEmpty()) return -1;

        return last.value;

    }

    public int pop() {

        if (isEmpty()) return -1;

        int ret = last.value;

        last = last.prev;

        return ret;

}   }

 

class StackFIFO extends StackArray {

    private StackArray temp = new StackArray();

    public int pop() {

        while ( ! isEmpty())

            temp.push( super.pop() );

        int ret =  temp.pop();

        while ( ! temp.isEmpty())

            push( temp.pop() );

        return ret;

}  }

 

class StackHanoi extends StackArray {

    private int totalRejected = 0;

    public int reportRejected()   { return totalRejected; }

    public void push( int in ) {

        if ( ! isEmpty()  &&  in > top())

            totalRejected++;

        else super.push( in );

}   }

 

class BridgeDisc {

    public static void main( String[] args ) {

        StackArray[] stacks = { new StackArray(), new StackFIFO(), new StackHanoi() };

        StackList    stack2 = new StackList();

        for (int i=1, num; i < 15; i++) {

            stacks[0].push( i );

            stack2.push( i );

            stacks[1].push( i );

        }

        java.util.Random rn = new java.util.Random();

        for (int i=1, num; i < 15; i++)

            stacks[2].push( rn.nextInt(20) );

        while ( ! stacks[0].isEmpty())

            System.out.print( stacks[0].pop() + "  " );

        System.out.println();

        while ( ! stack2.isEmpty())

            System.out.print( stack2.pop() + "  " );

        System.out.println();

        while ( ! stacks[1].isEmpty())

            System.out.print( stacks[1].pop() + "  " );

        System.out.println();

        while ( ! stacks[2].isEmpty())

            System.out.print( stacks[2].pop() + "  " );

        System.out.println();

        System.out.println( "total rejected is "

            + ((StackHanoi)stacks[2]).reportRejected() );

}   }