C Program for Inorder Preorder Postorder traversal of Binary Tree(Non Recursive)

By | 18.04.2017

Inorder Preorder Postorder traversal


Write a C Program for Inorder Preorder Postorder traversal of Binary Tree without Recursion. Here’s simple Program for Inorder Preorder Postorder traversal of Binary Tree ( Non Recursive ) in C Programming Language.


What is Tree ?


In linear data structure, data is organized in sequential order and in non-linear data structure, data is organized in random order. Tree is a very popular data structure used in wide range of applications.

A tree data structure can be defined as follows…

  • Tree is a non-linear data structure which organizes data in hierarchical structure and this is a recursive definition.

A tree data structure can also be defined as follows…

  • Tree data structure is a collection of data (Node) which is organized in hierarchical structure and this is a recursive definition.

Every individual element is called as Node. Node in a tree data structure, stores the actual data of that particular element and link to next element in hierarchical structure.


Below is the source code for C Program for Inorder Preorder Postorder traversal of Binary Tree without Recursion which is successfully compiled and run on Windows System to produce desired output as shown below :


SOURCE CODE : :


/*  C Program for Inorder Preorder Postorder traversal of Binary Tree */

#include<stdio.h>
#include<stdlib.h>
#define MAX 50

struct node
{
        struct node *lchild;
        int info;
        struct node *rchild;
};

struct node *insert_nrec(struct node *root, int ikey );
void nrec_pre(struct node *root);
void nrec_in(struct node *root);
void nrec_post(struct node *root);
void display(struct node *ptr,int level);

struct node *queue[MAX];
int front=-1,rear=-1;
void insert_queue(struct node *item);
struct node *del_queue();
int queue_empty();

struct node *stack[MAX];
int top=-1;
void push_stack(struct node *item);
struct node *pop_stack();
int stack_empty();

int main( )
{
        struct node *root=NULL, *ptr;
        int choice,k;

        while(1)
        {
                printf("\n");
                printf("1.Insert\n");
                printf("2.Display\n");
                printf("3.Preorder Traversal\n");
                printf("4.Inorder Traversal\n");
                printf("5.Postorder Traversal\n");
                printf("6.Quit\n");
                printf("\nEnter your choice : ");
                scanf("%d",&choice);

                switch(choice)
                {

                case 1:
                        printf("\nEnter the key to be inserted : ");
                        scanf("%d",&k);
                        root = insert_nrec(root, k);
                        break;

        case 2:
                        printf("\n");
                        display(root,0);
                        printf("\n");
                        break;

                case 3:
                        nrec_pre(root);
                        break;

                case 4:
                        nrec_in(root);
                        break;

                case 5:
                        nrec_post(root);
                        break;

                case 6:
                        exit(1);

                default:
                        printf("\nWrong choice\n");
                }/*End of switch*/
        }/*End of while */

        return 0;

}/*End of main( )*/


struct node *insert_nrec(struct node *root, int ikey)
{
        struct node *tmp,*par,*ptr;

        ptr = root;
        par = NULL;

        while( ptr!=NULL)
        {
                par = ptr;
                if(ikey < ptr->info)
                        ptr = ptr->lchild;
                else if( ikey > ptr->info )
                        ptr = ptr->rchild;
                else
                {
                        printf("\nDuplicate key");
                        return root;
                }
        }

        tmp=(struct node *)malloc(sizeof(struct node));
        tmp->info=ikey;
        tmp->lchild=NULL;
        tmp->rchild=NULL;

        if(par==NULL)
                root=tmp;
        else if( ikey < par->info )
                par->lchild=tmp;
        else
                par->rchild=tmp;

        return root;
}/*End of insert_nrec( )*/


void nrec_pre(struct node *root)
{
        struct node *ptr = root;
        if( ptr==NULL )
        {
                printf("Tree is empty\n");
                return;
        }
        push_stack(ptr);
        while( !stack_empty() )
        {
                ptr = pop_stack();
                printf("%d  ",ptr->info);
                if(ptr->rchild!=NULL)
                        push_stack(ptr->rchild);
                if(ptr->lchild!=NULL)
                        push_stack(ptr->lchild);
        }
        printf("\n");
}/*End of nrec_pre*/

void nrec_in(struct node *root)
{
        struct node *ptr=root;

        if( ptr==NULL )
        {
                printf("Tree is empty\n");
                return;
        }
        while(1)
        {
      while(ptr->lchild!=NULL )
                {
                        push_stack(ptr);
                        ptr = ptr->lchild;
                }

                while( ptr->rchild==NULL )
                {
                        printf("%d  ",ptr->info);
                        if(stack_empty())
                                return;
                        ptr = pop_stack();
                }
                printf("%d  ",ptr->info);
                ptr = ptr->rchild;
        }
        printf("\n");
}/*End of nrec_in( )*/

void nrec_post(struct node *root)
{
        struct node *ptr = root;
        struct node *q;

        if( ptr==NULL )
        {
                printf("Tree is empty\n");
                return;
        }
        q = root;
        while(1)
        {
                while(ptr->lchild!=NULL)
                {
                        push_stack(ptr);
                        ptr=ptr->lchild;
                }

                while( ptr->rchild==NULL || ptr->rchild==q )
                {
                        printf("%d  ",ptr->info);
                        q = ptr;
                        if( stack_empty() )
                                return;
                        ptr = pop_stack();
                }
                push_stack(ptr);
                ptr = ptr->rchild;
        }
        printf("\n");
}/*End of nrec_post( )*/


/*Functions for implementation of queue*/
void insert_queue(struct node *item)
{
        if(rear==MAX-1)
        {
                printf("Queue Overflow\n");
                return;
        }
        if(front==-1)  /*If queue is initially empty*/
                front=0;
        rear=rear+1;
        queue[rear]=item ;
}/*End of insert()*/

struct node *del_queue()
{
        struct node *item;
        if(front==-1 || front==rear+1)
        {
                printf("Queue Underflow\n");
                return 0;
        }
        item=queue[front];
        front=front+1;
        return item;
}/*End of del_queue()*/

int queue_empty()
{
        if(front==-1 || front==rear+1)
                return 1;
        else
                return 0;
}

/*Functions for implementation of stack*/
void push_stack(struct node *item)
{
        if(top==(MAX-1))
        {
                printf("Stack Overflow\n");
                return;
        }
        top=top+1;
        stack[top]=item;
}/*End of push_stack()*/

struct node *pop_stack()
{
        struct node *item;
        if(top==-1)
        {
                printf("Stack Underflow....\n");
                exit(1);
        }
        item=stack[top];
        top=top-1;
        return item;
}/*End of pop_stack()*/

int stack_empty()
{
        if(top==-1)
                return 1;
        else
                return 0;
} /*End of stack_empty*/


void display(struct node *ptr,int level)
{
        int i;
        if(ptr == NULL )/*Base Case*/
                return;
        else
    {
                display(ptr->rchild, level+1);
                printf("\n");
                for (i=0; i<level; i++)
                        printf("    ");
                printf("%d", ptr->info);
                display(ptr->lchild, level+1);
        }
}/*End of display()*/

OUTPUT : :


/*  C Program for Inorder Preorder Postorder traversal of Binary Tree */

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 7

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 5

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 6

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 4

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 9

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 8

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 1

Enter the key to be inserted : 11

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 2


        11
    9
        8
7
        6
    5
        4

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 3
7  5  4  6  9  8  11

1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 4
4  5  6  7  8  9  11
1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 5
4  6  5  8  11  9  7
1.Insert
2.Display
3.Preorder Traversal
4.Inorder Traversal
5.Postorder Traversal
6.Quit

Enter your choice : 6

Process returned 1

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Naina

I just needed this code!!! It was easy to understand. Used it as a reference to debug my code. Thank you.