Sum_to_leaf_numbers

/**
 * 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 sumNumbers(TreeNode* root) {
        if(!root) return 0;
        int sum=0;
        getSum(root,root->val,sum);
        return sum;
            
    }
    void getSum(TreeNode * root,int number,int &sum){
        if(root->left)
            getSum(root->left,number*10+root->left->val,sum);
        if(root->right)
            getSum(root->right,number*10+root->right->val,sum);
        if(!root->left&&!root->right){
            sum += number;
        }
    }
};