TheAlgorithms-C-Plus-Plus/Data Structure/MorrisInorder.cpp

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#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;
}