Merge pull request LetsGrowMoreCommunity#260 from soma2000-lang/kona

9_ All Possible Full Binary Trees.cpp

Trees/C++/9_ All Possible Full Binary Trees.cpp

@@ -0,0 +1,51 @@
+//Given an integer n, return a list of all possible full binary trees with n nodes. Each node of each tree in the answer must have Node.val == 0.
+
+//Each element of the answer is the root node of one possible tree. You may return the final list of trees in any order.
+
+//A full binary tree is a binary tree where each node has exactly 0 or 2 children.///
+
+
+Time Complexity: O(2^N)
+Space Complexity: O(2^N)
+
+#include <bits/stdc++.h>
+#include<iostream>
+using namespace std;
+
+    vector<TreeNode*> allPossibleFBT(int n) {
+
+        if(n&1 == 0)return {}; //FBT can have only odd number of nodes
+        if(n == 1)return {new TreeNode()};
+
+        vector<TreeNode*>res;
+
+        for(int i = 1; i < n-1;i+=2){  //incrementation by 2 to avoid redundant recursive call for even number of nodes
+
+            vector<TreeNode*>left = allPossibleFBT(i);
+            vector<TreeNode*>right = allPossibleFBT(n-i-1);  //1 is reserved for root node, hence n-i-1
+
+            for(auto l : left)
+                for(auto r : right)
+                    TreeNode* root = new TreeNode(), root->left = l, root->right = r, res.push_back(root);
+        }
+
+        return res;
+
+    } 
+};
+int main(){
+   vector<TreeNode*> v;//declaring a vector
+   for(TreeNode *t : v){
+      tree_level_trav(t);//calling the function
+   }
+}
+/*Input: n = 7
+Output: [[0,0,0,null,null,0,0,null,null,0,0],[0,0,0,null,null,0,0,0,0],[0,0,0,0,0,0,0],[0,0,0,0,0,null,null,null,null,0,0],[0,0,0,0,0,null,null,0,0]]
+Example 2:
+
+Input: n = 3
+Output: [[0,0,0]]
+
+Input: n = 5
+Output: [[0, 0, 0, null, null, 0, 0, null, null, null, null],
+[0, 0, 0, 0, 0, null, null, null, null, null, null]]/*