Python transforms a given list into a binary tree

when doing a problem on the Leetcode, there are a lot of binary tree related topics of the test data is given by the list, the time of submission will sometimes appear some data pass, this need to debug locally, so you need to use a list to build a binary tree, convenient debugging. The two-fork tree nodes on the Leetcode are defined as follows:

1 class TreeNode (object): 2     def __init__ (self, x): 3         Self.val = x4         self.left = None5         self.right = None

Use the list to build the binary tree, and the two-fork tree hierarchy traversal, the first sequence traversal, the middle sequence traversal, the post-order traversal code is as follows:

1  fromCollectionsImportdeque2 3 4 classTree (object):5     def __init__(self):6Self.root =None7     8     defConstruct_tree (Self, values=None):9         if  notvalues:Ten             returnNone OneSelf.root =TreeNode (values[0]) AQueue =deque ([self.root]) -Leng =len (values) -Nums = 1 the          whileNums <Leng: -node =Queue.popleft () -             ifnode: -Node.left = TreeNode (Values[nums])ifValues[nums]ElseNone + queue.append (node.left) -                 ifNums + 1 <Leng: +Node.right = TreeNode (values[nums+1])ifVALUES[NUMS+1]ElseNone A queue.append (node.right) atNums + = 1 -Nums + = 1 -      -     defBFS (self): -RET = [] -Queue =deque ([self.root]) in          whileQueue: -node =Queue.popleft () to             ifnode: + ret.append (node.val) - queue.append (node.left) the queue.append (node.right) *         returnret $ Panax Notoginseng     defpre_traversal (self): -RET = [] the  +         defTraversal (head): A             if  notHead: the                 return + ret.append (head.val) - Traversal (head.left) $ Traversal (head.right) $ Traversal (self.root) -         returnret -  the     defin_traversal (self): -RET = []Wuyi  the         defTraversal (head): -             if  notHead: Wu                 return - Traversal (head.left) About ret.append (head.val) $ Traversal (head.right) -  - Traversal (self.root) -         returnret A  +     defpost_traversal (self): theRET = [] -  $         defTraversal (head): the             if  notHead: the                 return the Traversal (head.left) the Traversal (head.right) - ret.append (head.val) in  the Traversal (self.root) the         returnRet

test and use:

1 t = Tree ()2 t.construct_tree ([1, 2, None, 4, 3, none, 5])3print c6> T.bfs ()4print  t.pre_traversal ()5print  t.in_ Traversal ()6print t.post_traversal ()

Python transforms a given list into a binary tree