题解 | #用两个栈实现队列#

import java.util.Stack;

public class Solution { Stack stack1 = new Stack(); Stack stack2 = new Stack();

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

public int pop() {
	if(stack1.empty()&&stack2.empty()){
        throw new RuntimeException("Queue is empty!");
    }
    if(stack2.empty()){
        while(!stack1.empty()){
            stack2.push(stack1.pop());
        }
    }
    return stack2.pop();
}

}