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/*
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 * Below is the interface for Iterator, which is already defined for you.
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 * **DO NOT** modify the interface for Iterator.
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 *
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 * class Iterator {
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 * struct Data;
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 * Data* data;
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 * public:
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 * Iterator(const vector<int>& nums);
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 * Iterator(const Iterator& iter);
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 *
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 * // Returns the next element in the iteration.
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 * int next();
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 *
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 * // Returns true if the iteration has more elements.
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 * bool hasNext() const;
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 * };
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 */
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class PeekingIterator : public Iterator {
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 public:
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  int _nextVal;
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  bool _hasNext;
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  PeekingIterator(const vector<int> &nums) : Iterator(nums) {
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    // Initialize any member here.
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    // **DO NOT** save a copy of nums and manipulate it directly.
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    // You should only use the Iterator interface methods.
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    _nextVal = 0;
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    _hasNext = Iterator::hasNext();
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    if (_hasNext) _nextVal = Iterator::next();
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  }
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  // Returns the next element in the iteration without advancing the iterator.
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  int peek() {
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    return (_nextVal);
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  }
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  // hasNext() and next() should behave the same as in the Iterator interface.
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  // Override them if needed.
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  int next() {
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    int tmp = _nextVal;
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    _hasNext = Iterator::hasNext();
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    if (_hasNext) _nextVal = Iterator::next();
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    return (tmp);
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  }
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  bool hasNext() const {
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    return (_hasNext);
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  }
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};