Leetcode: Zigzag Iterator

Question

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

For example, given two 1d vectors:

v1 = [1, 2]
v2 = [3, 4, 5, 6]
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?
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My Solution

class ZigzagIterator(object):    def __init__(self, v1, v2):        """        Initialize your data structure here.        :type v1: List[int]        :type v2: List[int]        """        self.v1, self.v2 = v1, v2        self.ind1, self.ind2 = 0,0        self.flag = 1    def next(self):        """        :rtype: int        """        if self.hasNext():            if self.ind1==len(self.v1) and self.ind2!=len(self.v2):                res = self.v2[self.ind2]                self.ind2 += 1            elif self.ind2==len(self.v2) and self.ind1!=len(self.v1):                res = self.v1[self.ind1]                self.ind1 += 1            else:                if self.flag==1:                    res = self.v1[self.ind1]                    self.ind1 += 1                    self.flag = 2                else:                    res = self.v2[self.ind2]                    self.ind2 += 1                    self.flag = 1            return res                        def hasNext(self):        """        :rtype: bool        """        if self.ind1==len(self.v1) and self.ind2==len(self.v2):            return False        else:            return True# Your ZigzagIterator object will be instantiated and called as such:# i, v = ZigzagIterator(v1, v2), []# while i.hasNext(): v.append(i.next())