Description

Submission

/**
 * 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 sumRootToLeaf(TreeNode* root) {
        return sumRootToLeafUtil(root, 0);
    }
    
    int sumRootToLeafUtil(TreeNode* root, int sum) {
        sum = (sum << 1) + root->val;
        if(root->left == nullptr && root->right == nullptr) return sum;
        int res = 0;
        if(root->left) res += sumRootToLeafUtil(root->left, sum);
        if(root->right) res += sumRootToLeafUtil(root->right, sum);
        return res;
    }
};