所谓遍历(Traversal)是指沿着某条搜索路线，依次对树中每个结点均做一次且仅做一次访问。访问结点所做的操作依赖于具体的应用问 题。 -The so-called ergodic (Traversal) refers to a search along the line, followed on each node in the tree are done once and only one visit. Access node operation done depends on the