Add 341_Flatten_Nested_List_Iterator.java

Author: Sean Prashad

Design/341_Flatten_Nested_List_Iterator.java

@@ -0,0 +1,32 @@
+public class NestedIterator implements Iterator<Integer> {
+    private Queue<NestedInteger> q;
+
+    public NestedIterator(List<NestedInteger> nestedList) {
+        q = new LinkedList<>();
+        flatten(nestedList);
+    }
+
+    private void flatten(List<NestedInteger> nestedList) {
+        if (nestedList == null) {
+            return;
+        }
+
+        for (NestedInteger n : nestedList) {
+            if (n.isInteger()) {
+                q.offer(n);
+            } else {
+                flatten(n.getList());
+            }
+        }
+    }
+
+    @Override
+    public Integer next() {
+        return hasNext() ? q.poll().getInteger() : null;
+    }
+
+    @Override
+    public boolean hasNext() {
+        return !q.isEmpty();
+    }
+}