leetcode Sum of Left Leaves

/**
 * 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 sumOfLeftLeaves(TreeNode* root) {
       
        return sumOfLeftHelp( root,0);

    }
    
    int sumOfLeftHelp(TreeNode* root,int isFromLeft)
    {
        if(!root)
        {
            return 0;
        }
        
        
        if(!root->left&&!root->right&&isFromLeft)
        {
            return root->val;
        }
        
        
        int sumofCurrent=0;
        if(root->left)
        {
            sumofCurrent+=sumOfLeftHelp(root->left,1);
        }
        
        if(root->right)
        {
            sumofCurrent+=sumOfLeftHelp(root->right,0);
        }
        return sumofCurrent;
    }
};