Random Iterator Mod 5

Description:

Example:

Note

Idea:

主要是注意一下取下一个数不能多次，所以next()和hasNext()要设计好。

Code:

只是个思想，这个程序跑不了，因为class Iterator没有implement。

#include <iostream>
#include <vector>
#include <climits>
#include <cassert>

using namespace std;

class Iterator {
public:
    Iterator(const vector<int>& nums);
    Iterator(const Iterator& iter);
    virtual ~Iterator();
    // Returns the next element in the iteration.
    int next();
    // Returns true if the iteration has more elements.
    bool hasNext();
    void remove();
};


class ModFiveIterator: public Iterator{
private:
    bool flag_called;
    bool flag_hasNext;
    int next_random;

public:
    ModFiveIterator(): flag_called(false), flag_hasNext(true) {}
    bool hasNext(){
        if(!flag_called){
            next_random=Iterator::next();
            while(Iterator::hasNext() && next_random%5!=0){
                next_random=Iterator::next();
            }
            flag_called=true;
            flag_hasNext = next_random%5==0 ? true: false;
        }

        return flag_hasNext;
    }

    int next(){
        if(!hasNext()) {
            throw runtime_error("no next.");
        }
        flag_called=false;
        return next_random;
    }
};