From 62834c14322fd42d27e381be8951b9c0ae61afde Mon Sep 17 00:00:00 2001
From: Shruti Sheoran <shruti.sheoran03@gmail.com>
Date: Thu, 11 Oct 2018 11:54:29 +0530
Subject: [PATCH] Add Morris Inorder Algorithm (Binary Tree)

---
 Datastructures/MorrisInorder.cpp | 94 ++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 Datastructures/MorrisInorder.cpp

diff --git a/Datastructures/MorrisInorder.cpp b/Datastructures/MorrisInorder.cpp
new file mode 100644
index 000000000..5ea630fac
--- /dev/null
+++ b/Datastructures/MorrisInorder.cpp
@@ -0,0 +1,94 @@
+#include <iostream>
+#include <queue>
+
+/**************************
+	@author shrutisheoran
+**************************/
+
+using namespace std;
+
+struct Btree {
+	int data;
+	struct Btree* left;   //Pointer to left subtree
+	struct Btree* right;  //Pointer to right subtree
+};
+
+void insert(Btree **root, int d) {
+	Btree *nn = new Btree();	//Creating new node
+	nn->data = d;
+	nn->left = NULL;
+	nn->right = NULL;
+	if(*root == NULL) {
+		*root = nn;
+		return;
+	}
+	else {
+		queue<Btree*> q;
+		// Adding root node to queue
+		q.push(*root);
+		while(!q.empty()) {
+			Btree *node = q.front();
+			// Removing parent node from queue
+			q.pop();
+			if(node->left)
+				// Adding left child of removed node to queue
+				q.push(node->left);
+			else {
+				// Adding new node if no left child is present
+				node->left = nn;
+				return;
+			}
+			if(node->right)
+				// Adding right child of removed node to queue
+				q.push(node->right);
+			else {
+				// Adding new node if no right child is present
+				node->right = nn;
+				return;
+			} 
+		}
+	}
+}
+
+void morrisInorder(Btree *root) {
+	Btree *curr = root;
+	Btree *temp;
+	while(curr) {
+		if(curr->left==NULL) {
+			cout<<curr->data<<" ";
+			// If left of current node is NULL then curr is shifted to right
+			curr = curr->right;
+		}
+		else {
+			// Left of current node is stored in temp
+			temp = curr->left;
+			// Moving to extreme right of temp
+			while(temp->right&&temp->right!=curr)
+				temp = temp->right;
+			// If extreme right is null it is made to point to currrent node (will be used for backtracking)
+			if(temp->right == NULL) {
+				temp->right = curr;
+				// current node is made to point its left subtree
+				curr = curr->left;
+			}
+			// If extreme right already points to currrent node it it set to null
+			else if(temp->right == curr) {
+				cout<<curr->data<<" ";
+				temp->right = NULL;
+				// current node is made to point its right subtree
+				curr = curr->right;
+			}
+		}
+	}
+}
+
+int main() {
+	// Testing morrisInorder funtion
+	Btree *root = NULL;
+	int i;
+	for(i = 1 ; i <= 7 ; i++)
+		insert(&root, i);
+	cout<<"Morris Inorder: ";
+	morrisInorder(root);
+	return 0;
+}