"""
Given two 1d vectors, implement an iterator to return their elements alternately.

Example:

Input:
v1 = [1,2]
v2 = [3,4,5,6]

Output: [1,3,2,4,5,6]

Explanation: By calling next repeatedly until hasNext returns false,
             the order of elements returned by next should be: [1,3,2,4,5,6].
Follow up: What if you are given k 1d vectors? How well can your code be extended to such cases?

Clarification for the follow up question:
The "Zigzag" order is not clearly defined and is ambiguous for k > 2 cases. If "Zigzag" does not look right to you, replace "Zigzag" with "Cyclic". For example:

Input:
[1,2,3]
[4,5,6,7]
[8,9]

Output: [1,4,8,2,5,9,3,6,7].
"""

class ZigzagIterator(object):

    def __init__(self, v1, v2):
        """
        Initialize your data structure here.
        :type v1: List[int]
        :type v2: List[int]
        """
        self.v1 = v1
        self.v2 = v2
        self.index_1 = 0
        self.index_2 = 0

    def next(self):
        """
        :rtype: int
        """
        if self.index_1 == len(self.v1):
            val = self.v2[self.index_2]
            self.index_2 += 1
        elif self.index_2 == len(self.v2):
            val = self.v1[self.index_1]
            self.index_1 += 1
        elif self.index_1 == self.index_2 or self.index_1 < self.index_2:
            val = self.v1[self.index_1]
            self.index_1 += 1
        else:
            val = self.v2[self.index_2]
            self.index_2 += 1
        return val

    def hasNext(self):
        """
        :rtype: bool
        """
        return self.index_1 < len(self.v1) or self.index_2 < len(self.v2)


# Your ZigzagIterator object will be instantiated and called as such:
# i, v = ZigzagIterator(v1, v2), []
# while i.hasNext(): v.append(i.next())