LeetCode232-用栈实现队列

LeetCode232-用栈实现队列

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class MyQueue {
private Stack<Integer> stack1;
private Stack<Integer> stack2;

public MyQueue() {
stack1 = new Stack<Integer>();
stack2 = new Stack<Integer>();
}

public void push(int x) {
stack1.push(x);
}

public int pop() {
if (stack2.isEmpty()) {
while (!stack1.isEmpty()) {
stack2.push(stack1.pop());
}
}

return stack2.pop();
}

public int peek() {
if (stack2.isEmpty()) {
while (!stack1.isEmpty()) {
stack2.push(stack1.pop());
}
}
return stack2.peek();
}

public boolean empty() {
return stack1.isEmpty() && stack2.isEmpty();
}
}