Added Binary Tree to Linked List.

Author: Sahil

Tree/Binary Tree to Linked List/cpp/BinaryTreeToLinkedList.cpp

@@ -0,0 +1,122 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Node{
+	public:
+		Node* left;
+		Node* right;
+		int data;
+		Node(int x){
+			data = x;
+			left = NULL;
+			right = NULL;
+		}
+};
+
+class Solution{
+	public:
+  		Node* insert(Node* root, int data) {
+            if(root == NULL) {
+                return new Node(data);
+            } else {
+                Node* cur;
+                if(data <= root->data) {
+                    cur = insert(root->left, data);
+                    root->left = cur;
+                } else {
+                    cur = insert(root->right, data);
+                    root->right = cur;
+               }
+
+               return root;
+           }
+        }
+
+		Node* flatten(Node* A) {
+		    if(!A)return NULL;
+
+		    // Take the left and right subtree
+		    Node* tempr = A->right;
+	        Node* templ = A->left;
+	        
+	        // Recursively Flatten them
+	        flatten(templ);
+	        flatten(tempr);
+
+	        // If left subtree exists, place it as the right subtree and make the right subtree
+	        // as the child of this new right subtree
+	        if(templ){
+	            A->right = templ;
+	            Node* x = templ;
+	            // Go to the end of the right subtree (which was earlier left subtree)
+	            while(x->right){
+	                x = x->right;
+	            }
+	            // Place the earlier right subtree as the right subtree of the current right subtree
+	            x->right = tempr;
+
+	            // Make the new left subtree as NULL
+	            templ->left = NULL;
+	        }
+	       	
+	       	// Nullify the left subtree.
+	       	A->left = NULL;
+
+	       	// Return the tree.
+	        return A;
+		}
+
+		void inOrder(Node* tree){
+			if(!tree) return;
+
+			inOrder(tree->left);
+			cout << tree->data << " " ;
+			inOrder(tree->right);
+		}
+};
+
+// Initial Tree:
+//			  4
+//			/	\
+//		   2	 7
+//	      /	\	/
+//	     1	 3 6
+
+// Final Tree:
+// 			  4
+// 			/	\
+//		   N     2
+//				/ \
+//			   N   1
+//	   			  / \
+//			     N   3
+//				    / \
+//			       N   7
+//				      / \
+//			         N   6
+// N - NULL
+
+
+int main() {
+	Solution myTree;
+	Node* root = NULL;
+	root = myTree.insert(root,4);
+	root = myTree.insert(root,2);
+	root = myTree.insert(root,3);
+	root = myTree.insert(root,1);
+	root = myTree.insert(root,7);
+	root = myTree.insert(root,6);
+	
+	cout << "InOrder Traversal is of the tree is as follows: " << endl;
+	myTree.inOrder(root);
+	cout << endl;
+	
+
+	myTree.flatten(root);
+	cout << "\n\nInOrder Traversal is of the flattened tree is as follows: " << endl;
+	myTree.inOrder(root);
+	cout << endl;
+	return 0;
+}
+