singlylinkedlist.c

//5

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

typedef struct NODE{
    int data;
    struct NODE*next;
}NODE;

NODE*create(){
    NODE*newNode=(NODE*)malloc(sizeof(NODE));
    if(newNode==NULL){
        printf("Memory allocation failed...\n");
        return newNode;
    }
    newNode->data=0;
    newNode->next=NULL;

    return newNode;
}

void display(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return;
    }

    NODE*temp=head->next;
    printf("\nLIST:\n");
    while(temp->next!=NULL){
        printf("%d-> ",temp->data);
        temp=temp->next;
    }
    printf("%d\n",temp->data);
}

NODE*insert_front(NODE*head){
    int val;
    printf("Enter the value to insert: ");
    scanf("%d",&val);
    NODE*newNode=create();
    newNode->data=val;
    newNode->next=head->next;
    head->next=newNode;
    head->data++;

    return head;
}

NODE*insert_rear(NODE*head){
    int val;
    printf("Enter the value to insert: ");
    scanf("%d",&val);
    NODE*newNode=create();
    newNode->data=val;

    NODE*temp=head;
    NODE*prev=temp;
    while(temp!=NULL){
        prev=temp;
        temp=temp->next;
    }
    prev->next=newNode;
    head->data++;
    return head;
}

NODE*delete_front(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }
    NODE*temp=head->next;
    head->next=temp->next;
    free(temp);
    head->data--;

    return head;
}

NODE*delete_rear(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }
    NODE*temp=head->next;
    NODE*prev=temp;

    while(temp->next!=NULL){
        prev=temp;
        temp=temp->next;
    }
    prev->next=NULL;
    free(temp);
    head->data--;
    return head;

}

NODE*insert_pos(NODE*head){
    int pos;
    printf("Enter the position to insert: ");
    scanf("%d",&pos);
    if(pos<1 || pos>head->data+1){
        printf("Invalid Position!\n");
        return head;
    }
    int val;
    printf("Enter the value to insert: ");
    scanf("%d",&val);
    NODE*newNode=create();
    newNode->data=val;
    NODE*temp=head;
    for(int i=1;i<pos;i++){
        temp=temp->next;
    }
    newNode->next=temp->next;
    temp->next=newNode;
    head->data++;
    return head;
}

NODE*delete_pos(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }
    int pos;
    printf("Enter position to delete: ");
    scanf("%d",&pos);
    if(pos<1 || pos>head->data){
        printf("Invalid Position!\n");
        return head;
    }
    NODE*temp=head->next;
    NODE*prev=head;

    for(int i=1;i<pos;i++){
        prev=temp;
        temp=temp->next;
    }
    prev->next=temp->next;
    free(temp);
    head->data--;

    return head;

}

NODE*delete_key(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }
    int key;
    printf("Enter the key to delete: ");
    scanf("%d",&key);

    int pos=search(head,key);
    if(pos==-1){
        printf("Key-> %d to delete not found\n",key);
        return head;
    }
    NODE*temp=head->next;
    NODE*prev=head;

    for(int i=1;i<pos;i++){
        prev=temp;
        temp=temp->next;
    }
    prev->next=temp->next;
    free(temp);
    head->data--;
    return head;
}

int search(NODE*head,int key){
    NODE*temp=head->next;
    int pos=0;
    while(temp!=NULL){
        pos++;
        if(temp->data==key){
            return pos;
        }
        temp=temp->next;
    }
    return -1;
}

void search_key(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return;
    }
    int key;
    printf("Enter key to search: ");
    scanf("%d",&key);

    int stat=search(head,key);

    if(stat==-1){
        printf("Search Unsuccessful!\nKey-> %d not found\n",key);
        return;
    }

    printf("Search Successful!\nKey-> %d found at position-> %d\n",key,stat);
    return;
}

NODE*orderlist(NODE*head){
    int val;
    printf("Enter the value to insert: ");
    scanf("%d",&val);
    NODE*newNode=create();
    newNode->data=val;
    NODE*temp=head;
    while(temp->next!=NULL && temp->next->data<=newNode->data){
        temp=temp->next;
    }
    newNode->next=temp->next;
    temp->next=newNode;
    head->data++;

    return head;

}

NODE*reverse(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }

    NODE*prev=NULL;
    NODE*current=head->next;
    NODE*next=NULL;

    while(current!=NULL){
        next=current->next;
        current->next=prev;
        prev=current;
        current=next;
    }
    head->next=prev;
    printf("List Reversed...\n");

    return head;
}

NODE*copy(NODE*head){
    if(head->data==0){
        printf("LIST EMPTY\n");
        return head;
    }
    NODE*newHead=create();
    NODE*temp=head->next;
    NODE*newtemp=newHead;
    while(temp!=NULL){
        NODE*newNode=create();
        newNode=temp;
        newtemp->next=newNode;
        newtemp=newtemp->next;
        temp=temp->next;
        newHead->data++;
    }
    printf("List copied...\n");
    return newHead;
}
void main(){
    NODE*head=create();
    int ch;
    for(;;){
        printf("\nENTER:\n1. To display\n2. To insert at front end\n3. To insert at rear end\n4. To delete at front end\n5. To delete at rear end\n6. To insert by position\n7. To delete by position\n8. To delete by key\n9. To search by key\n10. To create an ordered list\n11. To reverse the list\n12. To create a copy of the list\n");
        printf("Enter your choice from above: ");
        scanf("%d",&ch);

        switch(ch){

            case 1:
            display(head);
            break;

            case 2:
            head=insert_front(head);
            break;
            
            case 3:
            head=insert_rear(head);
            break;

            case 4:
            head=delete_front(head);
            break;

            case 5:
            head=delete_rear(head);
            break;

            case 6:
            head=insert_pos(head);
            break;

            case 7:
            head=delete_pos(head);
            break;

            case 8:
            head=delete_key(head);
            break;

            case 9:
            search_key(head);
            break;

            case 10:
            head=orderlist(head);
            break;

            case 11:
            head=reverse(head);
            break;

            case 12:
            head=copy(head);
            break;

            case 0:
            printf("Exiting...\n");
            free(head);
            exit(0);

            default:
            printf("Invalid Choice! Please Enter Again!...\n");


        }
    }
}