#include<stdio.h>
#include<stdlib.h>
typedef struct Linked {
int val;
struct Linked * next;
}
lnk;
lnk * insertbeg(lnk * , int);
lnk * insertend(lnk * , int);
lnk * insertatpos(lnk * , int, int);
lnk * del(lnk * , int);
void disp(lnk * );
lnk * insertbefore(lnk * , int);
void insertafter(lnk * , int);
int main() {
lnk * head = NULL;
int ch, v, p;
while (1) {
printf("\n1) Insert End\n2) Insert begining\n3) Insert at Position\n4) Insert after a certain node\n5) Insert before a certain node\n6) Delete\n7) Display\n8) Exit");
printf("\n Enter your choice : ");
scanf("%d", & ch);
switch (ch) {
case 1:
printf("\nEnter the value to be inserted : ");
scanf("%d", & v);
head = insertend(head, v);
break;
case 2:
printf("\nEnter the value to be inserted : ");
scanf("%d", & v);
head = insertbeg(head, v);
break;
case 3:
printf("\nEnter the value to be inserted : ");
scanf("%d", & v);
printf("\n Enter the position where to be inserted : ");
scanf("%d", & p);
head = insertatpos(head, v, p);
break;
case 4:
printf("\nEnter the value after which you want to Insert : ");
scanf("%d", & v);
insertafter(head, v);
break;
case 5:
printf("\nEnter the value before which you want to Insert : ");
scanf("%d", & v);
head = insertbefore(head, v);
break;
case 6:
printf("\n Enter the element to be deleted : ");
scanf("%d", & v);
head = del(head, v);
break;
case 7:
printf("\n Values in the linked list are : ");
disp(head);
break;
case 8:
exit(0);
default:
printf("\n Wrong choice ");
}
}
}
lnk * insertbeg(lnk * h, int g) {
lnk * temp;
temp = (lnk * ) malloc(sizeof(lnk));
temp -> val = g;
temp -> next = h;
h = temp;
return h;
}
lnk * insertend(lnk * h, int g) {
lnk * temp, * ptr;
temp = (lnk * ) malloc(sizeof(lnk));
temp -> val = g;
temp -> next = NULL;
if (h == NULL) {
printf("\n This is going to be first/head node");
h = temp;
} else {
ptr = h;
while (ptr -> next != NULL)
ptr = ptr -> next;
ptr -> next = temp;
}
return h;
}
lnk * insertatpos(lnk * h, int g, int p) {
lnk * ptr, * temp;
int i;
temp = (lnk * ) malloc(sizeof(lnk));
temp -> val = g;
temp -> next = NULL;
if (h == NULL) {
h = temp;
printf("\n This is going to be first/head node");
} else {
if (p == 1) {
temp -> next = h;
h = temp;
} else {
ptr = h;
for (i = 1; i < p - 1 && ptr != NULL; i++)
ptr = ptr -> next;
if (ptr == NULL) {
printf("\n There is no such location ");
return h;
} else {
temp -> next = ptr -> next;
ptr -> next = temp;
}
}
}
return h;
}
lnk * del(lnk * h, int g) {
lnk * pre, * ptr;
if (h == NULL) {
printf("\nNothing to delete");
return h;
} else {
if (h -> val == g) {
ptr = h;
h = h -> next;
} else {
ptr = h;
while (ptr != NULL && ptr -> val != g) {
pre = ptr;
ptr = ptr -> next;
}
if (ptr == NULL) {
printf("\n No Such element");
return h;
} else {
pre -> next = ptr -> next;
free(ptr);
}
}
}
return h;
}
void disp(lnk * h) {
while (h != NULL) {
printf("%d,", h -> val);
h = h -> next;
}
printf("\b");
}
lnk * insertbefore(lnk * h, int v) {
lnk * ptr, * pre, * temp;
int p;
printf("\nEnter the value of the inserting node:");
scanf("%d", & p);
temp = (lnk * ) malloc(sizeof(lnk));
temp -> val = p;
temp -> next = NULL;
if (h -> val == v) {
temp -> next = h;
h = temp;
} else {
ptr = h;
while (ptr -> val != v && ptr != NULL) {
pre = ptr;
ptr = ptr -> next;
}
temp -> next = pre -> next;
pre -> next = temp;
}
return h;
}
//insert a node after a particular node
void insertafter(lnk * h, int v) {
lnk * ptr, * temp;
int p;
ptr = h;
while (ptr -> val != v && ptr != NULL) {
ptr = ptr -> next;
}
printf("\nEnter the value of the inserting node:");
scanf("%d", & p);
temp = (lnk * ) malloc(sizeof(lnk));
temp -> next = NULL;
temp -> val = p;
printf("\n====================================");
if (ptr != NULL) {
temp -> next = ptr -> next;
ptr -> next = temp;
} else
printf("\nvalue not found");
}
