二叉树递归遍历的python实现

一、节点类的定义

class Node():     def __init__(self, data, left, right):                                               self.data = data                                                                    self.left = left                                                                    self.right = right

二、生成二叉树

class BTree:                                                                            def __init__(self):                                                                     self.root = None                                                                                                                      def insert(self, data):   #插入节点                                                           r = self.root                                                                    if r is None:                                                                        self.root = Node(data, None, None)                                              return                                                                          while True:                                                                             # 比根结点小放在左边                                                                if r.data > data:                                                                       if r.left is None:                                                                      r.left = Node(data, None, None)                                                 break                                                                           else:                                                                                   r = r.left                                                                  else:                                                                                   # 比根结点大放在右边                                                                if r.right is None:                                                                     r.right = Node(data, None, None)                                                break                                                                           else:                                                                                   r = r.right         

三、前序遍历

def preoder(self, root):                                                              if root is None:                                                                        return                                                                          else:                                                                                                                                              print root.data                                                                    self.preoder(root.left)                                      self.preoder(root.right)       

四、中序遍历

def midoder(self, root):                                                              if root is None:                                                                        return                                                                          else:                                                                                                                                                                                                      self.midoder(root.left)             print root.data                                     self.midoder(root.right)  

五、后序遍历

def postoder(self, root):                                                              if root is None:                                                                        return                                                                          else:                                                                                                                                                                                                      self.postoder(root.left)                                    self.postoder(root.right)             print root.data  

六、测试

if __name__ == '__main__':                                                              bt = BTree()    L=[3,7,5,8,9,10,11,2,6,4]    for i in L:                                            bt.insert(i)                                                                                                                           bt.preoder(bt.root)      bt.midoder(bt.root)     bt.postoder(bt.root)                                                       

七、总代吗

class Node():    def __init__(self,root):        self.root=root        self.lchild=None        self.rchild=Noneclass Bitree():    def __init__(self):        self.root=None    def insert(self,root,node):         #插入节点        if root:            if root.root>node.root:                if root.lchild:                    self.insert(root.lchild,node)                else:                    root.lchild=node            else:                 if root.rchild:                     self.insert(root.rchild,node)                 else:                     root.rchild=node        else:          return 0    def initBitree(self,data):        #生成二叉树        root=Node(data[0])        length=len(data)        for x in range(1,length):            node=Node(data[x])            self.insert(root,node)        return root    def preoder(self,root):       #先序遍历      if root:        print(root.root)        self.preoder(root.lchild)        self.preoder(root.rchild)    def midoder(self,root):      #中序遍历        if root:            self.midoder(root.lchild)            print(root.root)            self.midoder(root.rchild)    def postoder(self,root):      #后序遍历        if root:            self.postoder(root.lchild)            self.postoder(root.rchild)            print(root.root)if __name__ == '__main__':    data=[3,7,5,8,9,10,11,2,6,4]    Bitree=Bitree()    a=Bitree.initBitree(data)    print('前序遍历:')    Bitree.preoder(a)    print('中序遍历:')    Bitree.midoder(a)    print('后序遍历:')    Bitree.postoder(a)