题解 | #用两个栈实现队列#

public class Solution {
    Stack<Integer> stack1 = new Stack<Integer>();
    Stack<Integer> stack2 = new Stack<Integer>();
    
    public void push(int node) {
        stack1.push(node);
    }
    
    public int pop() {
        if(stack1.isEmpty()){
            return 0;
    }
      while(!stack1.isEmpty()){
          stack2.push(stack1.pop());
      }
        int node = stack2.pop();
        while(!stack2.isEmpty()){
          stack1.push(stack2.pop());
      }
        return node;
    }
}