LeetCode 538. 把二叉搜索树转换为累加树
原题链接
中等
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int sum = 0;
TreeNode* convertBST(TreeNode* root) {
if(!root) return root;
dfs(root);
return root;
}
void dfs(TreeNode* root) {
if(!root) return;
dfs(root->right);
sum += root->val;
root->val = sum;
dfs(root->left);
}
};