Peeking Iterator.cpp

/* 
    Solution by Rahul Surana
    
    ***********************************************************


Design an iterator that supports the peek operation on an existing iterator in addition to the hasNext and the next operations.

Implement the PeekingIterator class:

PeekingIterator(Iterator<int> nums) Initializes the object with the given integer iterator iterator.
int next() Returns the next element in the array and moves the pointer to the next element.
boolean hasNext() Returns true if there are still elements in the array.
int peek() Returns the next element in the array without moving the pointer.
Note: Each language may have a different implementation of the constructor and Iterator, 
but they all support the int next() and boolean hasNext() functions.



    ***********************************************************
*/



#include <bits/stdc++.h>

/*
 * 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 {
public:
    
    int i = 0;
    vector<int> n;
    
    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.
        n = nums;
        
        
    }
    
    // Returns the next element in the iteration without advancing the iterator.
    int peek() {
        return n[i];
    }
    
    // hasNext() and next() should behave the same as in the Iterator interface.
    // Override them if needed.
    int next() {
        return n[i++];
    }
    
    bool hasNext() const {
        return i<n.size();
    }
};