# Problem

Given two vectors of integers `v1`

and `v2`

, implement an iterator to return their elements alternately.

Implement the `ZigzagIterator`

class:

`ZigzagIterator(List<int> v1, List<int> v2)`

initializes the object with the two vectors`v1`

and`v2`

.`boolean hasNext()`

returns`true`

if the iterator still has elements, and`false`

otherwise.`int next()`

returns the current element of the iterator and moves the iterator to the next element.

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**Example 1:**

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].

**Example 2:**

Input:v1 = [1], v2 = []Output:[1]

**Example 3:**

Input:v1 = [], v2 = [1]Output:[1]

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**Constraints:**

`0 <= v1.length, v2.length <= 1000`

`1 <= v1.length + v2.length <= 2000`

`-2`

^{31}<= v1[i], v2[i] <= 2^{31}- 1

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**Follow up:** What if you are given `k`

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".

**Follow-up Example:**

Input:v1 = [1,2,3], v2 = [4,5,6,7], v3 = [8,9]Output:[1,4,8,2,5,9,3,6,7]