# Leetcode 284 Solution

This article provides solution to leetcode question 284 (peeking-iterator)

https://leetcode.com/problems/peeking-iterator

## Solution

``````// 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);
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 {
int m_next;
bool m_peeked;

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.
m_peeked = false;
}

// Returns the next element in the iteration without advancing the iterator.
int peek() {
if (m_peeked)
return m_next;
else
{
m_next = Iterator::next();
m_peeked = true;
return m_next;
}
}

// hasNext() and next() should behave the same as in the Iterator interface.
// Override them if needed.
int next() {
if (m_peeked)
{
m_peeked = false;
return m_next;
}
else
{
return Iterator::next();
}
}

bool hasNext() const {
if (m_peeked)
{
return true;
}
else
{
return Iterator::hasNext();
}
}
};
``````