peeking-iterator.cpp

// Below is the interface for Iterator, which is already defined for you.
// **DO NOT** modify the interface for Iterator.

// https://www.cnblogs.com/grandyang/p/4825068.html
// ?????????????????????????????????????????????????https://leetcode.com/problems/peeking-iterator/discuss/72554/Simple-C++-solution-(1-line-per-method)-without-extra-member-variables
class Iterator {
    struct Data;
	Data* data;
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() const;
};


class PeekingIterator : public Iterator {
public:
	PeekingIterator(const vector<int>& nums) : Iterator(nums) {
	    // Initialize any member here.
	    // **DO NOT** save a copy of nums and manipulate it directly.
	    // You should only use the Iterator interface methods.
	}

    // Returns the next element in the iteration without advancing the iterator.
	int peek() {
        return Iterator(*this).next();
	}

    // ????????????????
	// hasNext() and next() should behave the same as in the Iterator interface.
	// Override them if needed.
    /*
	int next() {
	    
	}

	bool hasNext() const {
	    
	}
    */
    
};