[LeetCode103] Binary Tree Zigzag Level Order Traversal (Medium)
Givenabinarytree,returnthezigzaglevelordertraversalofitsnodes'values.(ie,fromlefttoright,thenrighttoleftforthenextlevelandalternatebetween).Forexample:Givenbinarytree[3,9,20,null,null,15,7],3/\920/\15