二叉树 @ Python

二叉树 @ Python

# _*_coding:utf-8_*_

# 空节点
class TreeNode(object):
    def __init__(self):
        self.data = '#'
        self.left_child = None
        self.right_child = None


class Tree(object):
    def create_tree(self, treeNode):
        data = raw_input('->')
        if data == '#':
            # 表示该处没有节点存在
            treeNode = TreeNode()
        else:
            treeNode.data = data
            treeNode.left_child = TreeNode()
            treeNode.right_child = TreeNode()
            self.create_tree(treeNode.left_child)
            self.create_tree(treeNode.right_child)

    def visit(self, tree):
        if not tree.data == '#':
            print tree.data

    def pre_order(self, tree):
        if not tree.data == '#':
            self.visit(tree)
            self.visit(tree.left_child)
            self.visit(tree.right_child)

    def in_order(self, tree):
        if not tree.data == '#':
            self.visit(tree.left_child)
            self.visit(tree)
            self.visit(tree.right_child)

    def post_order(self, tree):
        if not tree.data == '#':
            self.visit(tree.left_child)
            self.visit(tree.right_child)
            self.visit(tree)


def main():
"""Example usage"""
    t = TreeNode()
    tree = Tree()
    tree.create_tree(t)
    tree.pre_order(t)
    print
    tree.in_order(t)
    print
    tree.post_order(t)
if __name__ == '__main__':
    main()