题解 | #用两个栈实现队列#

using System.Collections.Generic;
class Solution {
    Stack<int> stack1 = new Stack<int>();
    Stack<int> stack2 = new Stack<int>();
    public void push(int node) {
        if (stack1.Count == 0 && stack2.Count == 0) {
            stack1.Push(node);
        } else if (stack1.Count != 0 && stack2.Count == 0) {
            stack2.Push(node);
        } else if (stack1.Count != 0 && stack2.Count != 0) {
            while (stack2.Count != 0) {
                stack1.Push(stack2.Pop());
            }
            stack2.Push(node);
            while (stack1.Count != 1) {
                stack2.Push(stack1.Pop());
            }
        } else if (stack1.Count == 0 && stack2.Count != 0) {
            stack1.Push(stack2.Pop());
            stack2.Push(node);
        }
    }
    public int pop() {
        if (stack1.Count != 0) return stack1.Pop();
        return stack2.Pop();
    }
}