Insertion operation is used to insert an element in a binary tree at the desired location.
An element can only be inserted in a binary tree if the appropriate location is found. Therefore, the given element which is to be inserted is first compared with the root node. If the element is less than the root node then it is compared with the right child of the root node. In the same way, the element is compared in either of the subtrees until the desired location is found.
An insertion in a binary tree involves the following steps –
- Allocate the memory for the tree.
- Set the data part to the value and set the left and right pointers of the tree, point to NULL.
- If the item to be inserted, will be the first element of the tree, then the left and right of this node will point to NULL.
- Else, check if the item is less than the root element of the tree, if this is true, then recursively perform this operation with the left of the root.
- If this is false, then perform this operation recursively with the right sub-tree of the root.
Also check: spanning tree in data structure
Given below, is the algorithm for designing the insertion function for a binary tree –
IF TREE = NULL Allocate memory for TREE SET TREE -> DATA = ITEM SET TREE -> LEFT = TREE -> RIGHT = NULL ELSE IF ITEM < TREE -> DATA Insert(TREE -> LEFT, ITEM) ELSE Insert(TREE -> RIGHT, ITEM) [END OF IF] [END OF IF] END
Now, we will see the code for this
Insertion operation in a Binary Tree –
#include<stdio.h>
#include<stdlib.h>
void insert(int);
struct node
{
int data;
struct node *left;
struct node *right;
};
struct node *root;
void main ()
{
int choice,item;
do
{
printf("\nEnter the item which you want to insert?\n");
scanf("%d",&item);
insert(item);
printf("\nPress 0 to insert more ?\n");
scanf("%d",&choice);
}while(choice == 0);
}
void insert(int item)
{
struct node *ptr, *parentptr , *nodeptr;
ptr = (struct node *) malloc(sizeof (struct node));
if(ptr == NULL)
{
printf("can't insert");
}
else
{
ptr -> data = item;
ptr -> left = NULL;
ptr -> right = NULL;
if(root == NULL)
{
root = ptr;
root -> left = NULL;
root -> right = NULL;
}
else
{
parentptr = NULL;
nodeptr = root;
while(nodeptr != NULL)
{
parentptr = nodeptr;
if(item < nodeptr->data)
{
nodeptr = nodeptr -> left;
}
else
{
nodeptr = nodeptr -> right;
}
}
if(item < parentptr -> data)
{
parentptr -> left = ptr;
}
else
{
parentptr -> right = ptr;
}
}
printf("Node Inserted");
}
}
Also check: max heap deletion algorithm
