LeetCode:Implement Queue using Stacks

思路：两个栈实现一个队列

c++ code:

class Queue {
public:
    // Push element x to the back of queue.
    void push(int x) {
        s2.push(x);
    }

    // Removes the element from in front of queue.
    void pop(void) {
        if(s1.empty()) {
            while(!s2.empty()){
            int t = s2.top();
            s2.pop();
            s1.push(t);
            }
        }
        s1.pop();
    }

    // Get the front element.
    int peek(void) {
        if(s1.empty()) {
            while(!s2.empty()){
                int t = s2.top();
                s2.pop();
                s1.push(t);
            }
        }
        return s1.top();
    }

    // Return whether the queue is empty.
    bool empty(void) {
        if(s1.empty() && s2.empty()) return true;
        else return false;
    }
private:
    stack<int> s1,s2;
};

LeetCode:Implement Queue using Stacks

原文：http://blog.csdn.net/itismelzp/article/details/51473872