Optimizing binary search tree

Question

How could I optimize this binary search tree?

#include<stdio.h>
#include<stdlib.h>
struct NODE
{
 int info;
 struct NODE *right;
 struct NODE *left;
 struct NODE *parent;
};
typedef struct NODE node;
node *createnode(node *temp,int number)
{
 temp=(node*)malloc(sizeof(node));
 temp->info=number;
 temp->right=NULL;
 temp->left=NULL;
 temp->parent=NULL;
return temp;
}
node *insert(node *head,int number)
{
 node *temp;
 temp=createnode(temp,number);
 node *traverse=head;
 if(head==NULL)
 {
 head=temp;
 temp->parent=NULL;
 return head;
 }
 else
 {
 while(traverse!=NULL)
 {
 if(number < traverse->info)
 {
 if(traverse->left==NULL)
 {
 traverse->left=temp;
 temp->parent=traverse;
 break;
 }
 traverse=traverse->left;
 }
 else if(number>traverse->info)
 {
 if(traverse->right==NULL)
 {
 traverse->right=temp;
 temp->parent=traverse;
 break;
 }
 traverse=traverse->right;
 }
 else
 break;
 }
 }
return head;
}
node *find(node *head,int number) // finding the position of the element which we want to delete
{
 node *traverse=head;
 if(traverse==NULL)
 return NULL;
 else
 {
 while(traverse!=NULL)
 {
 if(number<traverse->info)
 {
 if(traverse->left==NULL)
 {
 printf("Number not found\n");
 return NULL;
 }
 traverse=traverse->left;
 }
 else if(number>traverse->info)
 {
 if(traverse->right==NULL)
 {
 printf("Number not found\n");
 return NULL;
 }
 traverse=traverse->right;
 }
 else
 break;
 }
 }
return traverse;
}
int find_children(node *temp) // finding the number of children of the the node that we want to delete
{
 int count=0;
 if(temp->left!=NULL)
 count+=1;
 if(temp->right!=NULL)
 count+=1;
return count;
}
node *delete(node *head,int number) //deleting the node
{
 int children;
 node *temp=head;
 temp=find(temp,number);
 if(temp==NULL)
 return head;
 else if(head->left==NULL && head->right==NULL)
 return NULL;
 else
 {
 children=find_children(temp);
 if(children==0)
 {
 if(temp->parent->left==temp)
 {
 temp->parent->left=NULL;
 }
 else if(temp->parent->right==temp)
 {
 temp->parent->right=NULL;
 }
 }
 if(children==1)
 {
 if(temp->parent==NULL)
 {
 if(temp->right!=NULL)
 {
 temp->right->parent=NULL;
 head=temp->right;
 }
 else if(temp->left!=NULL)
 {
 temp->left->parent=NULL;
 head=temp->left;
 }
 }
 else
 {
 if(temp->parent->left==temp)
 {
 if(temp->right!=NULL)
 {
 temp->right->parent=temp->parent;
 temp->parent->left=temp->right;
 }
 else if(temp->left!=NULL)
 {
 temp->left->parent=temp->parent;
 temp->parent->left=temp->left;
 }
 }
 if(temp->parent->right==temp)
 {
 if(temp->right!=NULL)
 {
 temp->right->parent=temp->parent;
 temp->parent->right=temp->right;
 }
 else if(temp->left!=NULL)
 {
 temp->left->parent=temp->parent;
 temp->parent->right=temp->left;
 }
 }
 }
 }
 if(children==2)
 {
 node *temp1;
 node *temp2;
 temp1=temp;
 temp2=temp->right;
 while(temp2->left!=NULL)
 {
 temp1=temp2;
 temp2=temp2->left;
 }
 temp->info=temp2->info;
 if(temp1->left==temp2)
 {
 temp1->left=temp2->left;
 }
 else
 {
 temp1->right=temp2->right;
 }
 }
 }
return head;
}
void printing(node *head)
{
 if(head==NULL)
 return ;
 printing(head->left);
 printf("%d ",head->info);
 printing(head->right);
}
int main()
{
 node *head;
 int number,choice;
 printf("Choose one of the option\n");
 while(1)
 {
 printf("\n1.Enter a element\n2.Delete an element\n3.print tree\n4.Exit\n");
 scanf("%d",&choice);
 switch(choice)
 {
 case 1:
 {
 scanf("%d",&number);
 head=insert(head,number);
 break;
 }
 case 2:
 {
 scanf("%d",&number);
 head=delete(head,number);
 break;
 }
 case 3:
 {
 printing(head);
 break;
 }
 case 4:
 {
 exit(0);
 break;
 }
 }
 }
 return 0;
}

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Answer 1

How could I optimize this binary search tree?

Higher-level suggestions:

• Forward declaration of the supported operations would be nice, so I can see them at a glance without scrolling through the entire post
• Given the current supported operations, NODE doesn't really need the parent. You could refactor and simplify without it
• In insert, you first create allocate a node, but it might not be used if the value already exists in the tree
• A naming convention for types would be good. node, in particular, is commonly used as variable name when working with trees, so it's confusing that it's actually a type
• find_children is poorly named. count_children would be better

Lower-level suggestions:

• temp is a poor name. Everywhere you used temp, node would have been better (unfortunately it was taken as a type name, as mentioned earlier)
• Instead of info a more common name to use for the data in a tree node is, well, data
• In many places you have if (condition) { return ...; } else { ...; }. When the if part returns, the else statement can be eliminated, which would often let you reduce the indent level of the rest of the routine, making it more readable
• return 0 is unnecessary in main, the compiler adds that automatically
• It's really odd to unindent the return statements. Usually it's at the same indent level as the body of the routine
• It's more readable to put spaces around operators, for example temp->left = NULL instead of temp->left=NULL, and if (head == NULL) instead of if(head==NULL), and if (number > traverse->info) instead of if(number>traverse->info)

The logic in most of the routines can be simplified. For example, consider this snippet in find:

node *traverse=head;
if(traverse==NULL)
 return NULL;
else
{
 while(traverse!=NULL)
 {
 // ...
 }
}
return traverse;

Could be simplified as this, without even knowing what's inside that while:

node *traverse = head;
while (traverse != NULL)
{
 // ...
}
return traverse;

Going further, the implementation of the routine can be reduced to a much more simplified form:

node *traverse = head;
while (traverse != NULL)
{
 if (number < traverse->info)
 {
 traverse = traverse->left;
 }
 else if (number > traverse->info)
 {
 traverse = traverse->right;
 }
 else
 {
 return traverse;
 }
}
printf("Number not found\n");
return NULL;

If you look closely, the other routines can be simplified as well.