LeetCode "Sum Root to Leaf Numbers"

class Solution {
public:
int dfs(TreeNode *p, int pval)
{
if( !p->left && !p->right )
{
int ssum = pval * 10 + p->val;
return ssum;
}

int rl = 0, rr = 0;
if(p->left)  rl = dfs(p->left, pval * 10 + p->val);
if(p->right) rr = dfs(p->right, pval * 10 + p->val);
return rl + rr;
}
int sumNumbers(TreeNode *root) {
int ret = 0;
if(root)    ret = dfs(root, 0);
return ret;
}
};