Inaccuracy in output of deletion function in binary search tree - data-structures

Question

I am making a binary search tree code, in that 'am facing an issue in the deletion function. After executing the function, the code is showing inorder display incorrectly. Basically, it is incorrect, and I'am not able to understand where the problem is.
In the delete function, I have used a search function that will find the node which the user has to delete. And I have used inorder successor method for deletion so the minimum function will find the successor. All other functions like insertion, minimum, and inorder are working fine.
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *left;
struct node *right;
} node;
struct node *insert(struct node *tnode, int data)
{
if (tnode == NULL)
{
struct node *ptr;
ptr = (struct node *)malloc(sizeof(struct node));
ptr->data = data;
ptr->left = NULL;
ptr->right = NULL;
return ptr;
}
if (data > (tnode->data))
{
tnode->right = insert(tnode->right, data);
return tnode;
}
if (data < (tnode->data))
{
tnode->left = insert(tnode->left, data);
return tnode;
}
}
void in_order(struct node *tnode)
{
if (tnode == NULL)
return;
else
{
in_order(tnode->left);
printf("%d\t", tnode->data);
in_order(tnode->right);
}
}
struct node *search(struct node *tnode, int data)
{
if (tnode == NULL)
{
return NULL;
}
else
{
if (data == tnode->data)
{
return tnode;
}
else
{
if (data > tnode->data)
{
search(tnode->right, data);
}
else
{
search(tnode->left, data);
}
}
}
}
struct node *minimum(struct node *tnode)
{
if (tnode == NULL)
{
printf("No node present\n");
return NULL;
}
else
{
if (tnode->left == NULL)
return tnode;
else
minimum(tnode->left);
}
}
struct node *deletenode(struct node *tnode, int data)
{
struct node *s;
s = search(tnode, data);
if (s == NULL)
{
printf("Value not found\n");
return NULL;
}
else
{
if (s->left == NULL && s->right == NULL) // No child case
{
free(s);
return NULL;
}
else
{
if (s->left == NULL && s->right != NULL) // single child case(right child)
{
struct node *temp = s->right;
free(s);
return temp;
}
else if (s->right == NULL && s->left != NULL) // single child case(left child)
{
struct node *temp = s->left;
free(s);
return temp;
}
else
{
struct node *temp;
temp = minimum(s->right);
s->data = temp->data;
s->right = deletenode(s->right, temp->data);
}
}
}
return s;
}
int main()
{
struct node *root = NULL, *del;
int n, i, data, key;
printf("Enter how many nodes you have to enter in a tree\n");
scanf("%d", &n);
for (i = 0; i < n; i++)
{
printf("Enter data\n");
scanf("%d", &data);
root = insert(root, data);
}
printf("\nIN-Order display\n");
in_order(root);
int d;
printf("\nEnter data to be delete\n");
scanf("%d", &d);
del=deletenode(root, d);
printf("\nIN-Order display\n");
in_order(root);
return 0;
}

Answer 1

There are several places missing return (in minimum, search and deletenode). You can easily find them if you compile with -Wall -Wextra compiler options.
It is not clear, what do you want to return from deletenode. I assume that it is a tree with deleted element. Then either search should return a parent node (so it is possible to change pointers to freed node), or deletenode should move to parent node.
Also, use in_order(del) instead of in_order(root) because root can be changed while deleting.