leetcode 剑指 Offer 09. 用两个栈实现队列

我的解答

/* Program to implement a stack
 using two queue */
#include <bits/stdc++.h>
using namespace std;

class CQueue
{
    stack<int> s1, s2;
public:
    CQueue()
    {

    }

    void appendTail(int value)
    {
        s1.push(value);
    }

    int deleteHead()
    {
        if (s1.empty() && s2.empty())
        {
            return -1;
        }
        if (s2.empty())
        {
            while (!s1.empty())
            {
                s2.push(s1.top());
                s1.pop();
            }
        }
        int ret = s2.top();
        s2.pop();
        return ret;
    }
};

/**
 * Your CQueue object will be instantiated and called as such:
 * CQueue* obj = new CQueue();
 * obj->appendTail(value);
 * int param_2 = obj->deleteHead();
 */
// Driver code
int main()
{
    CQueue q;
    for (int i = 0; i < 100; ++i)
    {
        q.appendTail(i);
    }
    for (int i = 0; i < 100; ++i)
    {
        cout << q.deleteHead() << ",";
    }
    cout << endl;
    return 0;
}
// g++ test.cpp