Question

I am creating a program to sort a list of names from a given text file using linked listed.

The text file would look something like this:

3 John Johnson

1 Tim Boring

1 Jason Mendoza

1 Bobert Reed

2 Tim Boring

4

5

Essentially I would like to associate each numerical value with an action: 1 = add a person, 2 = remove person, 3 = check if that name is in the list, 4 = print list, 5 = exit.

I've been having trouble sorting the list once the linked list is established.

Here's an example of what I was going for:

void sortList(node *head)

{

node *i, *j;

int temp;

for(i=head; i->next!=NULL; i=i->next)

{

for(j=i->next; j!=NULL; j=j->next)

{

if(i->data > j->data)

{

temp = i->data

i->data = j->data;

j->data = temp;

}

}

}

}

general assistance of the overall program and samples would be greatly appreciated.

Answer 1

//C++ program

#include<iostream>
using namespace std;

struct Node{
   string data;
   struct Node*next;
};

void insert(struct Node **head, string data)
{
struct Node *ptr1 = new struct Node;
ptr1->data = data;
ptr1->next = *head;
*head = ptr1;
}
void remove(struct Node **head, string key)
{
struct Node* temp = *head, *prev;
  
if (temp != NULL && temp->data == key)
{
*head = temp->next;   
delete(temp);
return;
}
while (temp != NULL && temp->data != key)
{
prev = temp;
temp = temp->next;
}
  
if (temp == NULL) {
   cout<<key<< " not found in list\n";
   return;
   }
prev->next = temp->next;
  
delete(temp);
}

void printList(struct Node *head)
{
struct Node *temp = head;
cout<<"\n";
while (temp!=NULL)
{
cout<< temp->data<<" ";
temp = temp->next;
}
}

bool search (struct Node*head , string key){
   struct Node*temp=head;
  
   while(temp){
       if(temp->data==key)return true;
       temp=temp->next;
   }
   return false;
}

/* function to swap data of two nodes a and b*/
void swap(struct Node *a, struct Node *b)
{
string temp = a->data;
a->data = b->data;
b->data = temp;
}

void bubbleSort(struct Node *head)
{
int swapped, i;
struct Node *ptr1;
struct Node *lptr = NULL;
  
if (!head)
return;
  
do
{
swapped = 0;
ptr1 = head;
  
while (ptr1->next != lptr)
{
if (ptr1->data > ptr1->next->data)
{
swap(ptr1, ptr1->next);
swapped = 1;
}
ptr1 = ptr1->next;
}
lptr = ptr1;
}
while (swapped);
}

int main(){
   int choice;
   string name;
   struct Node *head = NULL;
   do{
       cout<<"1 = add a person\n2 = remove person\n3 = check if that name is in the list\n4 = print list\n5 = exit\n";
       cout<<"Enter choice : ";
       cin>>choice;
       switch(choice){
           case 1:{
               cout<<"Enter name: ";
               cin.ignore();
               getline(cin,name);
               insert(&head,name);
               break;
           }
           case 2:{
               cout<<"Enter name: ";
               cin.ignore();
               getline(cin,name);
               remove(&head,name);
               break;
           }
           case 3:{
               cout<<"Enter name: ";
               cin.ignore();
               getline(cin,name);
               if(search(head,name))cout<<name<<" is in the list\n";
               else cout<<name<<" is not in the list\n";
               break;
           }
           case 4:{
               cout<<"Your list is : \n";
               printList(head);
               cout<<"\n";
              
               break;
           }
           case 5:{
               cout<<"Goodbye!\n";
               break;
           }
           default:{
               cout<<"Invalid choice\n";
               cout<<"Re-enter your choice\n";
               break;
           }
       }
      
   }while(choice!=5);
  
   return 0;
}