SWAPPING OF LEFT AND RIGHT SUBTREES OF A GIVEN BINARY TREE

Program

#include <stdio.h>
#include <stdlib.h>
struct tnode
{
  int data;
  struct tnode *lchild, *rchild;
};

struct tnode *insert(struct tnode *p,int val)
{
   struct tnode *temp1,*temp2;
   if(p == NULL)
   {
         p = (struct tnode *) malloc(sizeof(struct tnode)); /* insert the new node as root node*/
         if(p == NULL)
           {
      printf("Cannot allocate\n");
      exit(0);
          }
       p->data = val;
       p->lchild=p->rchild=NULL;
   }
  else
  {
    temp1 = p;
   /* traverse the tree to get a pointer to that node whose child will be the newly created node*/
  while(temp1 != NULL)
  {
    temp2 = temp1;
    if( temp1 ->data > val)
         temp1 = temp1->lchild;
    else
         temp1 = temp1->rchild;
  }
  if( temp2->data > val)
  {
     temp2->lchild = (struct tnode*)malloc(sizeof(struct tnode));/ *inserts the newly created node
  as left child*/
     temp2 = temp2->lchild;
     if(temp2 == NULL)
          {
      printf("Cannot allocate\n");
      exit(0);
           }
       temp2->data = val;
       temp2->lchild=temp2->rchild = NULL;
  }
  else
  {
     temp2->rchild = (struct tnode*)malloc(sizeof(struct tnode));/ *inserts the newly created node
  as left child*/
     temp2 = temp2->rchild;
     if(temp2 == NULL)
          {
     printf("Cannot allocate\n");
     exit(0);
          }
     temp2->data = val;
     temp2->lchild=temp2->rchild = NULL;
}
}
return(p);
}
/* a function to binary tree in inorder */
void inorder(struct tnode *p)
    {
       if(p != NULL)
         {
            inorder(p->lchild);
           printf("%d\t",p->data);
          inorder(p->rchild);
          }
      }
struct tnode *swaptree(struct tnode *p)
{
   struct tnode *temp1=NULL, *temp2=NULL;
   if( p != NULL)
   { temp1= swaptree(p->lchild);
                  temp2 = swaptree(p->rchild);
              p->rchild = temp1;
               p->lchild = temp2;
     }
     return(p);
  }

void main()
{
  struct tnode *root = NULL;
  int n,x;
  printf("Enter the number of nodes\n");
  scanf("%d",&n);
  while( n - > 0)
  {
    printf("Enter the data value\n");
    scanf("%d",&x);
    root = insert(root,x);
 }
   printf("The created tree is :\n");
   inorder(root);
   printf("The tree after swapping is :\n");
   root = swaptree(root);
   inorder(root);
   printf("\nThe original tree is \n");
   root = swaptree(root);
   inorder(root);
}

Explanation

• Input: 1. The number of nodes that the tree to be created should have
  2. The data values of each node in the tree to be created
• Output: 1. The data value of the nodes of the tree in inorder before interchanging the left and right subtrees
  2. The data value of the nodes of the tree in inorder after interchanging the left and right subtrees