Python3數據結構之樹的定義、添加節點、遍歷

# coding:utf-8

class Node(object):
    def __init__(self, item):
        self.elem = item
        self.lchild = None
        self.rchild = None


class Tree(object):
    # 初始化
    def __init__(self):
        self.root = None

    # 廣度遍歷
    def breadthTravel(self):
        if self.root is None:
            return
        queue = []  # 隊列
        queue.append(self.root)  # 入隊
        while queue:
            current_node = queue.pop(0)  # 出隊
            print(current_node.elem,end='')
            if current_node.lchild is not None:
                queue.append(current_node.lchild)
            if current_node.rchild is not None:
                queue.append(current_node.rchild)

    def preOrder(self, node):  # 傳遞根是爲了遞歸把每棵樹的子樹的根傳入
        if node is None:
            return
        print(node.elem,end='')
        self.preOrder(node.lchild)
        self.preOrder(node.rchild)

    def inOrder(self, node):
        if node is None:
            return
        self.inOrder(node.lchild)
        print(node.elem,end='')
        self.inOrder(node.rchild)

    def postOrder(self,node):
        if node is None:
            return
        self.postOrder(node.lchild)
        self.postOrder(node.rchild)
        print(node.elem,end='')

    # 樹的添加結點
    def add(self, item):
        node = Node(item)
        if self.root is None:  # 根節點是否本身爲空
            self.root = node
            return
        queue = []  # 隊列
        queue.append(self.root)  # 入隊
        while queue:  # 當列表不爲空
            current_node = queue.pop(0)  # 出隊
            if current_node.lchild is None:
                current_node.lchild = node
                return
            else:
                queue.append(current_node.lchild)
            if current_node.rchild is None:
                current_node.rchild = node
                return
            else:
                queue.append(current_node.rchild)



if __name__ == "__main__":
    tree = Tree()
    tree.add(1)
    tree.add(2)
    tree.add(3)
    tree.add(4)
    tree.add(5)
    tree.add(6)
    tree.add(7)
    tree.add(8)
    tree.add(9)
    tree.breadthTravel()
    print('')
    tree.preOrder(tree.root)
    print('')
    tree.inOrder(tree.root)
    print('')
    tree.postOrder(tree.root)