0341-0350 341. Flatten Nested List Iterator ⋆⋆\star\star⋆⋆ 342. Power of Four ⋆\star⋆ 343. Integer Break ⋆⋆\star\star⋆⋆ 344. Reverse String ⋆\star⋆ 345. Reverse Vowels of a String ⋆\star⋆ 346. Moving Average from Data Stream ⋆\star⋆ 347. Top K Frequent Elements ⋆⋆\star\star⋆⋆ 348. Design Tic-Tac-Toe ⋆⋆\star\star⋆⋆ 349. Intersection of Two Arrays ⋆\star⋆ 350. Intersection of Two Arrays II ⋆\star⋆