【LeetCode】Sum Root to Leaf Numbers

/**
 * Definition for binary tree
 * struct TreeNode {
 * int val;
 * TreeNode *left;
 * TreeNode *right;
 * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int getsum(TreeNode *root, int sum)
    {
        if(NULL==root->left&&NULL==root->right) return sum*10+root->val;
        sum=((root->left)?(getsum(root->left,sum*10+root->val)):0)
            +((root->right)?(getsum(root->right,sum*10+root->val)):0);
        return sum;
    }
    int sumNumbers(TreeNode *root) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(NULL==root) return 0;
        int sum=getsum(root, 0);
        return sum;
    }
};