/*
* Below is the interface for Iterator, which is already defined for you.
* **DO NOT** modify the interface for Iterator.
*
* class Iterator {
* struct Data;
* Data* data;
* public:
* Iterator(const vector<int>& nums);
* Iterator(const Iterator& iter);
*
* // Returns the next element in the iteration.
* int next();
*
* // Returns true if the iteration has more elements.
* bool hasNext() const;
* };
*/
class PeekingIterator : public Iterator {
private:
int _next;
bool _hasNext;
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.
_next = Iterator::next();
_hasNext = Iterator::hasNext();
}
// Returns the next element in the iteration without advancing the iterator.
int peek() {
return _next;
}
// hasNext() and next() should behave the same as in the Iterator interface.
// Override them if needed.
int next() {
int val = _next;
_hasNext = Iterator::hasNext();
if (_hasNext) {
_next = Iterator::next();
}
return val;
}
bool hasNext() const {
return _hasNext;
}
};