栈和队列的互相实现

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两个栈实现一个队列

public class TwoStackImpAQuene {
public Stack<Integer> s1;//进队的栈
public Stack<Integer> s2;//出队的栈

public void push(int num){
    s1.push(num);
}

public int size(){
    return s1.size()+s2.size();
}

public int pop() throws Exception{
    if (s2.isEmpty()){
        while (!s1.isEmpty()){
            s2.push(s1.pop());
        }
    }
    if (s2.isEmpty()){
        throw  new Exception("队列为空");
    }

    return s2.pop();
****}
}

两个队列是实现一个栈

public class TwoQueneImpStack {
LinkedList<Integer> queue1 = new LinkedList();
LinkedList<Integer> queue2 = new LinkedList();

public void push(int value){
    queue1.addLast(value);
}

public int size(){
    return queue1.size()+queue2.size();
}

public int pop() throws Exception{
    if (size()!=0){
        if (!queue1.isEmpty()){
            putOneToAnother();//q1的值只留一个其余放到空的q2中
            return queue1.removeFirst();
        }
        if (!queue2.isEmpty()){
            putOneToAnother();//q2的值只留一个其余放到空的q1中
            return queue2.removeFirst();
        }
    }
    throw new Exception("空了");
}


public void putOneToAnother(){
    if (!queue1.isEmpty()){
        while (queue1.size()>1){
            queue2.addLast(queue1.removeFirst());
        }
    }else if (!queue2.isEmpty()){
        while (queue2.size()>1){
            queue1.addLast(queue2.removeFirst());
        }
    }
}
}
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