```
# I have a problem in building class Tree (Binary Search)
# function DelNode(self, Key) is not exactly
# I Need Help, Please building class Tree (Binary Search)
# Is there any different definition of class Tree
from string import split
class Node:
def __init__(self):
self.Key = None
self.pLeft = None
self.pRight = None
def __del__(self):
del self
class Tree:
def __init__(self):
self.Root = None
def __del__a(self):
if self.Root != None:
del self.Root.pLeft
del self.Root.pRight
del self.Root
def LNR(self):
if self.Root != None:
self.Root.pLeft.LNR()
print self.Root.Key,
self.Root.pRight.LNR()
def InsertNode(self, Key):
if self.Root != None:
if self.Root.Key == Key:
return 0
elif self.Root.Key > Key:
return self.Root.pLeft.InsertNode(Key)
else:
return self.Root.pRight.InsertNode(Key)
self.Root = Node()
if self.Root == None:
return -1
self.Root.Key = Key
self.Root.pLeft = Tree()
self.Root.pRight = Tree()
return 1
def SearchStandFor(self, t1, t2):
if t2.Root.pLeft.Root != None:
self.SearchStandFor(t1, t2.Root.pLeft)
else:
t1.Root.Key = t2.Root.Key
t1 = t2
t2 = t2.Root.pRight
def DelNode(self, Key):
if self.Root == None:
return 0
if self.Root.Key > Key:
return self.Root.pLeft.DelNode(Key)
elif self.Root.Key < Key:
return self.Root.pRight.DelNode(Key)
else:# self.Root.Key == Key
p = self # --> trouble ???
if self.Root.pLeft.Root == None:
self.Root = self.Root.pRight.Root
elif self.Root.pRight.Root == None:
self.Root = self.Root.pLeft.Root
else:# Root has 2 children
self.SearchStandFor(p, self.Root.pRight)
del p # --> trouble ???
return 1
def ReadFile(strFileName, t):
OFile = open(strFileName, "r")
text = OFile.readline()
OFile.close()
a = split(text, " ")
for i in range(0,len(a)):
t.InsertNode(int(a[i]))
def main():
print
t = Tree()
ReadFile("TreeIn.txt", t)
t.LNR() #--> 13 16 18 31 37 40 44 55 59 71 81 108
print
t.DelNode(44) # 44 is root, have two children
t.LNR() #--> 13 16 18 31 37 40 55 55 59 71 81 108
# I write t.DelNode(13), it don't run exactly, 13 is a node have 1 child (right child)
# ... and if I don't define function __del__ of clas Node, it runs exactly, why???
main()
#content of file TreeIn.txt is "44 18 37 13 31 40 81 59 108 55 71 16"
```

## Recommended Answers

Jump to PostIf you insist writing your own destructor for class Tree, change it to this:

`class Tree: def __init__(self): self.Root = None def __del__(self): if self.Root != None: del self.Root def LNR(self): ... ...`

Note: Destructors are optional thing in Python.

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