From 8ede6390a02d828e510c7a4e8148aa28e41fb85a Mon Sep 17 00:00:00 2001
From: Karan Singh <55060123+Karan227@users.noreply.github.com>
Date: Tue, 7 Sep 2021 11:17:06 +0530
Subject: [PATCH] Create Unique-Binary-Search-TreesII.cpp

---
 C++/Unique-Binary-Search-TreesII.cpp | 43 ++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 C++/Unique-Binary-Search-TreesII.cpp

diff --git a/C++/Unique-Binary-Search-TreesII.cpp b/C++/Unique-Binary-Search-TreesII.cpp
new file mode 100644
index 0000000000..e0de9e2fa2
--- /dev/null
+++ b/C++/Unique-Binary-Search-TreesII.cpp
@@ -0,0 +1,43 @@
+/**
+ * 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:
+    vector<TreeNode*> generateTrees(int n) 
+    {
+        vector<vector<TreeNode*>> dp(n + 1);
+        dp[0].emplace_back(nullptr);
+        for (int i = 1; i <= n; i++) 
+        {
+            for (int j = 1; j <= i; j++) 
+            {
+                for (auto l : dp[j - 1]) 
+                {
+                    for (auto r : dp[i - j]) {
+                        auto m = new TreeNode(j, l, r);
+                        dp[i].emplace_back(m);
+                    }
+                }
+            }
+        }
+        function<void(TreeNode*&, int)> replace = [&] (TreeNode *&p, int val) 
+        {
+            if (!p) return;
+            p = new TreeNode(p->val + val, p->left, p->right);
+            replace(p->left, val);
+            replace(p->right, p->val);
+        }; 
+        for (auto &t : dp[n])
+            replace(t, 0);
+        return dp[n];
+    }
+};