lintcode 12 带最小值操作的栈

class MinStack {
public:
    stack<int> num;
    stack<int> mins;
    MinStack() {
        // do intialization if necessary
    }

    /*
     * @param number: An integer
     * @return: nothing
     */
    void push(int number) {
        // write your code here
        if( mins.size()==0 || mins.top() >= number) {
            mins.push(number);
        } else {
            mins.push(mins.top());
        }
        num.push(number);
    }

    /*
     * @return: An integer
     */
    int pop() {
        // write your code here
        int t;
        if(mins.size()>0 && num.size()>0){
            t=num.top();
            num.pop();
            mins.pop();
            return t;
        } else {
            return 0;
        }
    }

    /*
     * @return: An integer
     */
    int min() {
        // write your code here
        if(mins.size() > 0 && num.size()>0){
            return mins.top();
        }
        return 0;
    }
};