Python实现深度优先与广度优先

class Node(object):
    """初始化一个节点,需要为节点设置值"""
    def __init__(self, val):
        self.val = val
        self.left = None
        self.right = None

class BinaryTree(object):
    """
    创建二叉树,完成
    - 添加元素
    - 广度遍历
    - 深度遍历(先序遍历, 中序遍历, 后序遍历)
    """
    def __init__(self):
        self.root = None
        pass

    # 添加元素
    def addNode(self, val):
        # 创建队列结构存储结点
        nodeStack = [self.root,]

        # 如果根结点为空
        if self.root == None:
            self.root = Node(val)
            print("添加根节点{0}成功!".format(self.root.val))
            return


        while len(nodeStack) > 0:
            # 队列元素出列
            p_node = nodeStack.pop()

            # 如果左子结点为空
            if p_node.left == None:
                p_node.left = Node(val)
                print("添加左:{0} ".format(p_node.left.val))
                return

            # 如果右子节点为空
            if p_node.right == None:
                p_node.right = Node(val)
                print("添加右:{0} ".format(p_node.right.val))
                return

            nodeStack.insert(0, p_node.left)
            nodeStack.insert(0, p_node.right)

    # 广度遍历(中序: 先读父节点,再读左子节点, 右子节点)
    def breadthFirst(self):
        nodeStack = [self.root, ];

        while len(nodeStack) > 0:
            my_node = nodeStack.pop()
            print("-->",my_node.val)

            if my_node.left is not None:
                nodeStack.insert(0, my_node.left)

            if my_node.right is not None:
                nodeStack.insert(0, my_node.right)

    # 深度优先(先序遍历)

    def preorder(self, start_node):

        if start_node == None:
            return

        print(start_node.val)
        self.preorder(start_node.left)
        self.preorder(start_node.right)


    # 深度优先(中序遍历)
    def inorder(self, start_node):
        if start_node == None:
            return

        self.inorder(start_node.left)
        print(start_node.val)
        self.inorder(start_node.right)

    # 深度优先(后序遍历)
    def outorder(self, start_node):
        if start_node == None:
            return
        self.outorder(start_node.left)
        self.outorder(start_node.right)
        print(start_node.val)

def main():
    bt = BinaryTree()
    bt.addNode(0)
    bt.addNode(1)
    bt.addNode(2)
    bt.addNode(3)
    bt.addNode(4)
    bt.addNode(5)
    bt.addNode(6)
    bt.addNode(7)
    bt.addNode(8)
    bt.addNode(9)

    print("广度遍历-->")
    bt.breadthFirst()
    
    print("先序遍历-->")
    bt.preorder(bt.root)

    print("中序遍历-->")
    bt.inorder(bt.root)
    
    print("后序遍历-->")
    bt.outorder(bt.root)

if __name__ == '__main__':
    main()