7.4 树遍历:level2 & Zigzag & *recover* B & sameT & symmeT
todoXORcondition:if(!A!=!B),!isforbooleanconversion,andcarefulofcomplieroptimization,maybe2]BinaryTreeZigzagLevelOrderTraversal写的太慢了,mark重写vector>zigzagLevelOrder(TreeNode*root){if(!root)returnvector>