Leetcode#112 Path Sum

bool solve(TreeNode *root, int sum) {
if (!root->left && !root->right)
return sum == root->val;

return (root->left && solve(root->left, sum - root->val)) || (root->right && solve(root->right, sum - root->val));
}

bool hasPathSum(TreeNode *root, int sum) {
if (!root)
return false;

return solve(root, sum);
}