Find Successor

• Time : O(n)
• Space : O(1)

using namespace std;

// This is an input class. Do not edit.
class BinaryTree {
public:
  int value;
  BinaryTree *left = nullptr;
  BinaryTree *right = nullptr;
  BinaryTree *parent = nullptr;

  BinaryTree(int value) { this->value = value; }
};
void helper(BinaryTree* node, BinaryTree* target, BinaryTree** res, bool& search) {
	if(!node or *res != nullptr) return;
	helper(node->left, target, res, search);
	if(search) {*res = node; search = false;}
	if(target == node) search = true;
	helper(node->right, target, res, search);
	
}
BinaryTree *findSuccessor(BinaryTree *tree, BinaryTree *node) {
  BinaryTree* res = nullptr;
	bool search = false;
	helper(tree, node, &res, search);
  return res;
}