完全二叉树求节点个数

最新推荐文章于 2023-06-07 15:19:06 发布

独孤金泽

最新推荐文章于 2023-06-07 15:19:06 发布

阅读量1k

点赞数

CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/qq_35747066/article/details/90298877

博客围绕计算完全二叉树的节点数量展开，介绍了完全二叉树的定义，即除最后一层外每一层都完全填满，最后一层节点尽量靠左，最后一层节点数在1到2h之间（h为最后一层）。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

222. Count Complete Tree Nodes

Medium

922124FavoriteShare

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

Note:

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.

Example:

Input: 
    1
   / \
  2   3
 / \  /
4  5 6

Output: 6

class Solution {
public:
    int countNodes(TreeNode* root) {
        TreeNode* LeftNode = root;
        TreeNode* RightNode = root;
        int LeftNum = 0;
        int RightNum = 0;
        while(LeftNode){
            LeftNum++;
            LeftNode = LeftNode->left;
        }
        while(RightNode){
            RightNum++;
            RightNode = RightNode->right;
        }
        if(RightNum == LeftNum){
            return pow(2,RightNum) - 1;
        }
        else{
            return countNodes(root->left) + countNodes(root->right) + 1;
        }
    }
};