LeetCode #429 N-ary Tree Level Order Traversal N叉树的层序遍历
Description:Givenann-arytree,returnthelevelordertraversalofitsnodes'values.(ie,fromlefttoright,levelbylevel).Forexample,givena3-arytree:3-arytreeWeshouldreturnitslevelordertraversal:[[1],[3,2,4],[5,6]