LeetCode 222. 完全二叉树的节点个数 (遍历+打编号)

完全二叉树的节点个数

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int ans = 0; int countNodes(TreeNode* root) { dfs(root,1); return ans; } void dfs(TreeNode* root,int idx){ if(!root){ return; } ans = max(ans,idx); dfs(root->left,idx<<1); dfs(root->right,(idx<<1)|1); } };