Implement an iterator for a nested list (flatten a nested list of integers)?

Short answer: public class NestedIterator { private Queue<int> queue; public NestedIterator(IList<NestedInteger> nestedList) { queue = new Queue<int>(); Flatten(nestedList); } private void Flatten(IList<NestedInteger> nestedList) { foreach (var ni in nestedList) { if (ni.IsInteger()) queue.Enqueue(ni.GetInteger()); else Flatten(ni.GetList()); } } public bool HasNext() { return queue.Count > 0; } public int Next() { return…

Explain a bit more

queue.Dequeue(); } } Note: NestedInteger is an interface with methods: IsInteger(), GetInteger(), GetList(). Explanation: Pre-flatten the nested list into a queue and iterate over it. Follow on:

Example code

public class NestedIterator {
private Queue<int> queue;
public NestedIterator(IList<NestedInteger> nestedList) {
queue = new Queue<int>(); Flatten(nestedList); }
private void Flatten(IList<NestedInteger> nestedList) {
foreach (var ni in nestedList) {
if (ni.IsInteger()) queue.Enqueue(ni.GetInteger()); else Flatten(ni.GetList()); }
}
public bool HasNext() {
return queue.Count > 0;
}
public int Next() {
return queue.Dequeue();
}
} Note: NestedInteger is an interface with methods: IsInteger(), GetInteger(), GetList(). Explanation: Pre-flatten the nested list into a queue and iterate over it. Follow on:

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.