Leetcode-222题:Count|Leetcode-222题:Count Complete Tree Nodes

题目:Given a complete binary tree, count the number of nodes.

Definition of a complete binary tree from Wikipedia:
In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.
思路:如果知道一个子树是完全二叉树,并且其深度为h,那么这棵子树所包含的节点个数便为2^h-1。否则便需递归求其左右子树的节点个数。
【Leetcode-222题:Count|Leetcode-222题:Count Complete Tree Nodes】代码:
def getHightRight(self, root): if root == None: return 0 high = 0 while root != None: high += 1 root = root.right return highdef getHightLeft(self, root): if root == None: return 0 high = 0 while root != None: high += 1 root = root.left return highdef countNodes(self, root): """ :type root: TreeNode :rtype: int """ if root == None: return 0 l_high = self.getHightLeft(root.left) r_high = self.getHightRight(root.right) if l_high == r_high: return 2**(l_high+1)-1 else: return self.countNodes(root.left)+self.countNodes(root.right)+1

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