38.二叉树的寻找 插入

#二叉树的插入,寻找。如果有就不用插入，如果没有就插入
class tree:
    def __init__(self):
        self.data=0
        self.left=None
        self.right=None
def create_tree(root,val):
    newnode=tree()
    newnode.data=val
    if root==None:
        root=newnode
        return root
    else:
        current=root
        while current!=None:
            backup=current
            if current.data>val:
                current=current.left
            else:
                current=current.right
        if backup.data>val:
            backup.left=newnode
        else:
            backup.right=newnode
    return root
def search(ptr,data):#先查找有没有，，没有的话再插入
    i = 1
    while True:

        if ptr==None:
            return ptr
        if ptr.data==data:
            print('通过[%d]次找到'%i)
            return ptr
        elif ptr.data>data:
            ptr=ptr.left
        else:
            ptr=ptr.right
        i+=1
def midorder(ptr):#中序遍历
    if ptr!=None:
        midorder(ptr.left)
        print('中序法排序为%d'%ptr.data)
        midorder(ptr.right)
data=[7,1,4,2,8,13,12,11,15,9,5]
ptr=None
lookfor=13
for i in range(len(data)):
    ptr=create_tree(ptr,data[i])
result=search(ptr,lookfor)
if result==None:
    print('没有找到')
    ptr = create_tree(ptr, lookfor)
else:
    print("不用插入")
midorder(ptr)

参考图解数据结构书