# Construct String from Binary Tree Problem & Solution

## C++ Solution

``````#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")
#pragma GCC target("avx,avx2,fma")

static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

/**
* Definition for a binary tree node.
* struct TreeNode {
*   int val;
*   TreeNode *left;
*   TreeNode *right;
*   TreeNode() : val(0), left(nullptr), right(nullptr) {}
*   TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
*   TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
string tree2str(TreeNode* root) {
string s;
tree2str(root, s);

return s;
}

private:
void tree2str(TreeNode* root, string& s) {
if (root == nullptr) {
return;
}

s += to_string(root->val);
if (root->left != nullptr) {
s += "(";
tree2str(root->left, s);
s += ")";
}

if (root->left == nullptr && root->right != nullptr) {
s += "()";
}

if (root->right != nullptr) {
s += "(";
tree2str(root->right, s);
s += ")";
}
}
};
``````