LeetCode Q281: Zigzag Iterator

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:

	class ZigzagIterator {
	public:
	ZigzagIterator(vector<int>& _v1, vector<int>& _v2) {
	v.push_back(_v1);
	v.push_back(_v2);
	size[0]=v[0].size();
	size[1]=v[1].size();
	p[0]=0;
	p[1]=0;
	nowat=0;
	}
	int next() {
	int res=v[nowat][p[nowat]];
	p[nowat]++;
	nowat = nowat^1;
	return res;
	}
	bool hasNext() {
	if(p[nowat]>=size[nowat]){
	nowat = nowat^1;
	return p[nowat]<size[nowat];
	}
	return true;
	}
	vector<vector<int>> v;
	int size[2];
	int p[2];
	int nowat;
	};

view raw Q281.cpp hosted with ❤ by GitHub