281. Zigzag Iterator

第一遍这里报了一个错
原因是在next()第一行 Iterator 应当写成 Iterator<Integer>
这里用LinkedList是为了扩展到k个list
如果只是两个list的话可以简单地用一个swap
public int next() { if (j.hasNext()) { tmp = j; j = i; i = tmp; } return i.next(); }

Line 11: error: incompatible types: Object cannot be converted to int

28.58%
public class ZigzagIterator {
    private LinkedList<Iterator<Integer>> list;
    public ZigzagIterator(List<Integer> v1, List<Integer> v2) {
        list = new LinkedList<Iterator<Integer>>();
        if (!v1.isEmpty()) list.add(v1.iterator());
        if (!v2.isEmpty()) list.add(v2.iterator());
    }

    public int next() {
        Iterator<Integer> iter = list.remove();
        int result = iter.next();
        if (iter.hasNext()) list.add(iter);
        return result;
    }

    public boolean hasNext() {
        return !list.isEmpty();
    }
}

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