Peeking Iterator

Problem: Peeking Iterator

To get the property similar to peeking iterator, we just fetch and store next() of regular iterator and move regular iterator one step forward as our peeking iterator.

Code in Python:

class PeekingIterator(object):
    def __init__(self, iterator):
        self.iter = iterator
        self.temp = self.iter.next() if self.iter.hasNext() else None

    def peek(self):
        return self.temp

    def next(self):
        ret = self.temp
        self.temp = self.iter.next() if self.iter.hasNext() else None
        return ret

    def hasNext(self):
        return self.temp is not None