# 281. Zigzag Iterator

### Problem:

```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?

Clarification for the follow up question - Update (2015-09-18):
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, given the following input:

[1,2,3]
[4,5,6,7]
[8,9]
It should return [1,4,8,2,5,9,3,6,7].
```

### Solutions:

``````public class ZigzagIterator {
public ZigzagIterator(List<Integer> v1, List<Integer> v2) {
if (v1.size() > 0) {
}
if (v2.size() > 0) {
}
}

public int next() {
Iterator<Integer> it = its.poll();
int res = it.next();
if (it.hasNext()) {
}
return res;
}

public boolean hasNext() {
return its.size() > 0;
}
}

/**
* Your ZigzagIterator object will be instantiated and called as such:
* ZigzagIterator i = new ZigzagIterator(v1, v2);
* while (i.hasNext()) v[f()] = i.next();
*/
``````