Implement Stack using Queues
2772 ワード
まだ2つのqueueがして、書いていません
class MyStack {
public Queue<Integer> q = new LinkedList<Integer>();
//cc150 ，
// single queue
public void push(int x) {
q.add((int) x);
}
// Removes the element on top of the stack.
public void pop() {
if(q.isEmpty()) return;
for(int i=0;i<q.size()-1;i++){
q.add(q.peek());
q.poll();
}
int re = q.peek();
q.poll();
}
// Get the top element.
public int top() {
if(q.size()<=1) return q.peek();
for(int i=0;i<q.size()-1;i++){
q.add(q.peek());
q.poll();
}
int re = q.peek();
q.add(re);
q.poll();
return re;
}
// Return whether the stack is empty.
public boolean empty() {
return q.isEmpty() ;
}
}