static bool _hasPathSum(Node<T> const* node, int sum) {
// strategy: enumerate all root-to-leaf paths (or rather the sum of
// the r-t-l paths) and check
if (node == nullptr) {
return sum == 0;
} else {
sum -= node->value;
return _hasPathSum(node->left, sum) || _hasPathSum(node->right, sum);
}
}
bool _hasPathSum(TreeNode *root, int sum) {
if (!root->left && !root->right && root->val == sum) return true;
bool res = false;
if (root->left) {
res = res || _hasPathSum(root->left, sum - root->val);
}
if (res) return true;
if (root->right) {
res = res || _hasPathSum(root->right, sum - root->val);
}
return res;
}
bool hasPathSum(TreeNode *root, int sum) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if (!root) return false;
return _hasPathSum(root, sum);
}
