281. Zigzag Iterator
Given two 1d vectors, implement an iterator to return their elements alternately.
Example:
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]
.
Follow up: What if you are given k
1d vectors? How well can your code be extended to such cases?
Clarificationfor 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". For example:
Input:
[1,2,3]
[4,5,6,7]
[8,9]
Output:
[1,4,8,2,5,9,3,6,7]
.
Solution
(1) Java
public class ZigzagIterator {
Deque<Iterator<Integer>> iterq = new LinkedList<>();
public ZigzagIterator(List<Integer> v1, List<Integer> v2) {
if (v1.size() > 0) {
iterq.offer(v1.iterator());
}
if (v2.size() > 0) {
iterq.offer(v2.iterator());
}
}
public int next() {
Iterator<Integer> iter = iterq.poll();
int rst = iter.next();
if (iter.hasNext()) {
iterq.offer(iter);
}
return rst;
}
public boolean hasNext() {
return !iterq.isEmpty();
}
}
/**
* Your ZigzagIterator object will be instantiated and called as such:
* ZigzagIterator i = new ZigzagIterator(v1, v2);
* while (i.hasNext()) v[f()] = i.next();
*/
(2) Python
(3) Scala