九.二叉树

向右看齐 2023-02-17 15:56 26阅读 0赞

原文链接:https://www.cnblogs.com/bobo-zhang/p/10856009.html

#  #

[ 11.二叉树 ][11._]

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 <div class="clear"></div>
 <div class="postBody">

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*

![复制代码][Image 1]

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’)

![复制代码][Image 1]

python实现排序二叉树：

![复制代码][Image 1]

#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’)

</pre>

![复制代码][Image 1]

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