C program to implement Tree data structure and its operations

Simple C program to implement Tree data structure having following operations:

• Insert a value
• Inorder Display
• Preorder Display
• Postorder Display
• Search An Element
• Delete An Element

Code:

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>


struct node{
int data;
struct node *left;
struct node *right;
};


struct node *root;


struct node *newnode(){
int val;
printf("\nEnter the value to be inserted:");
scanf("%d",&val);
struct node *temp;
temp=(struct node*)malloc(sizeof(struct node));
temp->left=NULL;
temp->right=NULL;
temp->data=val;
return temp;
}


void insert(struct node *root, struct node *root2) {
if (root2->data <= root->data) {
if (root->left == NULL)
root->left = root2;
else
insert(root->left, root2);
}


if (root2->data > root->data) {
if (root->right == NULL)
root->right = root2;
else
insert(root->right, root2);
}
}




void displayi(struct node *temp) {
if(temp!=NULL) {
displayi(temp->left);
printf("\t%d", temp->data);
displayi(temp->right);
}
}


void displaypre(struct node *temp) {
if(temp != NULL) {
printf("\t%d", temp->data);
displaypre(temp->right);
displaypre(temp->left);
}
}


void displaypost(struct node *temp) {
if(temp != NULL) {
displaypost(temp->left);
displaypost(temp->right);
printf("\t%d", temp->data);
}
}




struct node* search(struct node* root, int key)
{


if (root == NULL || root->data == key)
return root;




if (root->data < key)
return search(root->right, key);




return search(root->left, key);
}








struct node *min(struct node* temp)
{
struct node* temp2 = temp;
while (temp2->left != NULL)
temp2 = temp2->left;


return temp2;
}






struct node* deletee(struct node* root, int key)
{


if (root == NULL) return root;




if (key < root->data)
root->left = deletee(root->left, key);


else if (key > root->data)
root->right = deletee(root->right, key);


else
{


if (root->left == NULL)
{
struct node *temp = root->right;
free(root);
return temp;
}
else if (root->right == NULL)
{
struct node *temp = root->left;
free(root);
return temp;
}




struct node* temp = min(root->right);
root->data = temp->data;
root->right = deletee(root->right, temp->data);
}
return root;
}








main(){
root=NULL;
int opt,val;
struct node *temp,*answer;
printf("*****Operations on tree******\n");
printf("1. Insert a value");
printf("\t2. Inorder Display");
printf("\t3. Preorder Display");
printf("\t4. Postorder Display");
printf("\t5. Search An Element");
printf("\t6. Delete An Element");
printf("\t7. Exit\n");
do{
printf("\nEnter your choice: ");
scanf("%d",&opt);




switch(opt){
case 1:


temp=newnode();
if(root==NULL){root=temp;}
else{insert(root,temp);}
break;
case 2:
if (root==NULL)
{printf("tree is empty!\n");}
else {
printf("\ninorder:");
displayi(root);
printf("\n");
}
break;
case 3:
if (root==NULL)
{printf("tree is empty!\n");}
else {
printf("\npreorder:");
displaypre(root);
printf("\n");
}
break;
case 4:
if (root==NULL)
{printf("tree is empty!\n");}
else {
printf("\npostorder:");
displaypost(root);
printf("\n");
}
break;




case 5:
printf("Enter the value to be searched: ");
scanf("%d",&val);
struct node *root2=root;
answer=search(root2,val);
if(answer==NULL){printf("Value not found!");}
else {printf("Search found: %d",answer->data);}
break;




case 6:
printf("Enter the value to be deleted: ");
scanf("%d",&val);
struct node *root3=root;
if(root3==NULL){printf("Tree s empty!");}
else {deletee(root3,val);}
break;






case 7:
break;
default:printf("Wrong choice!\n");
break;
}


}while(opt!=7);
printf("End");
}