11.二叉树

python实现二叉树的数据结构:

  . 二叉树的排序方式:

    - 广度遍历(层次遍历)

    - 深度遍历:
      - 前序(根左右):把根放到最前面
      - 中序(左根右):把根放到中间
      - 后序(左右根):把根放到最后

class Node():
    def __init__(self,item):
        self.item = item
        self.right = None
        self.left = None
class Tree():
    def __init__(self):
        self.root = None
    def add(self,item):
        node = Node(item)
        if self.root is None:
            self.root = node
            return
        else:
            queue = [self.root]
            while queue:
                cur = queue.pop(0)
                if cur.left is None:
                    cur.left = node
                    return
                else:
                    queue.append(cur.left)
                if cur.right is None:
                    cur.right = node
                    return
                else:
                    queue.append(cur.right)
    #广度遍历
    def travel(self):
        if self.root is None:
            print('')
            return
        else:
            queue = [self.root]
            while queue:
                cur = queue.pop(0)
                print(cur.item)
                if cur.left is not None:
                    queue.append(cur.left)
                if cur.right is not None:
                    queue.append(cur.right)
                    
    #深度遍历:前序,中序,后序遍历
    def forwordTravel(self,root):
        if root is None:
            return
        print(root.item,end=' ')
        self.forwordTravel(root.left)
        self.forwordTravel(root.right)
        
    def middleTravel(self,root):
        if root is None:
            return
        self.middleTravel(root.left)
        print(root.item,end=' ')
        self.middleTravel(root.right)
        
    def backTravel(self,root):
        if root is None:
            return
        self.backTravel(root.left)
        self.backTravel(root.right)
        print(root.item,end=' ')
                
tree = Tree()
tree.add('0')
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.travel()
tree.forwordTravel(tree.root)
print('\n')
tree.backTravel(tree.root)
print('\n')
tree.middleTravel(tree.root)
print('\n')

 

python实现排序二叉树:

#排序二叉树
class Node():
    def __init__(self,item):
        self.item = item
        self.left = None
        self.right = None
class Tree():
    def __init__(self):
        self.root = None
    def insert(self,item):
        node = Node(item)
        cur = self.root
        if cur is None:
            self.root = node
            return
        while True:
            if item < cur.item:
                if cur.left is None:
                    cur.left = node
                    return
                else:
                    cur = cur.left
            else:
                if cur.right is None:
                    cur.right = node
                    return
                else:
                    cur = cur.right
    def preTravel(self,root):
        if root is None:
            return
        print(root.item,end=' ')
        self.preTravel(root.left)
        self.preTravel(root.right)
    def middleTravel(self,root):
        if root is None:
            return
        self.middleTravel(root.left)
        print(root.item,end=' ')
        self.middleTravel(root.right)
    def backTravel(self,root):
        if root is None:
            return
        self.backTravel(root.left)
        self.backTravel(root.right)
        print(root.item,end=' ')
        
tree = Tree()
tree.insert(3)
tree.insert(8)
tree.insert(5)
tree.insert(7)
tree.insert(6)
tree.preTravel(tree.root)
print('\n')
tree.middleTravel(tree.root)
print('\n')
tree.backTravel(tree.root)
print('\n')

            

 

posted @ 2019-05-13 12:46  波晓张  阅读(426)  评论(0编辑  收藏