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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Thanks for reading the post….
I just needed this code!!! It was easy to understand. Used it as a reference to debug my code. Thank you.