404 sum of left leaves

Find the sum of all left leaves in a given binary tree.

Example:

    3
   / \
  9  20
    /  \
   15   7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.



int sumOfLeftLeaves(struct TreeNode* root) {
    
        if (!root) return 0;
        if (root->left && !root->left->left && !root->left->right)
            return root->left->val + sumOfLeftLeaves(root->right);
        return sumOfLeftLeaves(root->left) + sumOfLeftLeaves(root->right);
}