class MyStack {
private Queue<Integer> queue1;
private Queue<Integer> queue2;
private int size;
/** Initialize your data structure here. */
public MyStack() {
this.queue1 = new LinkedList<Integer>();
this.queue2 = new LinkedList<Integer>();
this.size = 0;
}
/** Push element x onto stack. */
public void push(int x) {
if(queue1.peek() != null){
queue1.offer(x);
}else if(queue2.peek() != null){
queue2.offer(x);
}else{
//都为空，则用queue1开始
queue1.offer(x);
}
size++;
}
/** Removes the element on top of the stack and returns that element. */
public int pop() {
if(empty()){
throw new RuntimeException("无数据");
}
int e = 0;
if(queue2.peek() != null){
for(int i = 0; i < size - 1; i++){
queue1.offer(queue2.poll());
}
e = queue2.poll();
}else{
for(int i = 0; i < size - 1; i++){
queue2.offer(queue1.poll());
}
e = queue1.poll();
}
this.size--;
return e;
}
/** Get the top element. */
public int top() {
if(empty()){
throw new RuntimeException("无数据");
}
int e = 0;
if(queue2.peek() != null){
for(int i = 0; i < size; i++){
e = queue2.poll();
queue1.offer(e);
}
}else{
for(int i = 0; i < size; i++){
e = queue1.poll();
queue2.offer(e);
}
}
return e;
}
/** Returns whether the stack is empty. */
public boolean empty() {
return size == 0;
}
public int size(){
return this.size;
}
}
