Question

Linked Lists

Problem 1
Implement a program that reads the following ages (type int) from text file ages.txt and stores
them in a linked list:
16 18 22 24 15 31 27 19 13
Implement the class LinkedList along with any applicable member functions (e.g. void
insert(int num)).
Perform the following actions on the list (if applicable, use recursion):
1. Display the data in the list
2. Insert 18 at the front of the list
3. Insert 23 at the end of the list
4. Insert 25 after the number 24
5. Compute the average age
6. Sort the ages in ascending order
7. Determine how many people are 18 or older

Problem 2
Implement a program that reads the following data (two strings, one double) from text file
balances.txt and stores it in a linked list:
John Miller 2508.13
Carolyn Spacer 188.54
Mark Lee 1816.82
Sophia Brown 3200.68
Jim Gomez 12068.34
Carlos Mendoza 783.41
Erica Robertson 2000.67
Implement the class LinkedList along with any applicable member functions (e.g. void
moveToEnd(string fullName)).
Perform the following actions on the list:
1. Display the data in the list
2. Remove the person with the lowest balance
3. Display the name and balance of the person with the most money
4. Display the average balance of people with a balance of $2,000 or more
5. Find Sophia Brown and move her to the end of the list (use multipurpose helper
functions to make this easier)

Answer 1

#include<stdio.h>

#include<stdlib.h>

struct Node

{

int value;

struct Node *next;

};

void insert_in_front(struct Node **head,int data)

{

// allocate new node

struct Node *new_node = (struct Node*)malloc(sizeof(struct Node));

//put the data into it

new_node->value = data;

//since it is new head, attached the linked list to it's back

new_node->next = *head;

// make it new head

*head = new_node;

}

void insert_in_end(struct Node **head, int data)

{

//allocate the new node

struct Node *new_node = (struct Node*)malloc(sizeof(struct Node));

//put the data into it

new_node->value = data;

//since it is going to be last node, it's next pointer will be null

new_node->next = NULL;

struct Node *last = *head;

// if initial list was null the new_node will become head of the linked list

if(*head==NULL)

{

*head = new_node;

return;

}

// traverse to end of the list

while(last->next!=NULL)

{

last = last->next;

}

// adding the node to end of the list

last->next = new_node;

return;

}

void insert_after(struct Node **head,int prev_data,int data)

{

//allocate new node

struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));

//put data into it

new_node->value = data;

//finding the previous node

struct Node* prev_node = *head;

while(prev_node->value!=prev_data)

{

prev_node = prev_node->next;

}

//make next of new node as next of previous node

new_node->next = prev_node->next;

//make the next of previous node as head of new node

prev_node->next = new_node;

return ;

}

void display(struct Node* node)

{

while(node->next!=NULL)

{

printf("%d -> ",node->value);

node = node->next;

}

printf("%d\n",node->value);

}

float average_age(struct Node* node)

{

if(node==NULL)return 0;

int sum=0;

int count=0;

while(node!=NULL)

{

sum+=node->value;

count++;

node=node->next;

}

return (float)sum/count;

}

int greater_than(struct Node* node,int value)

{

int ans=0;

while(node!=NULL)

{

if(node->value>=18)ans++;

node=node->next;

}

return ans;

}

void swap(struct Node* a,struct Node* b)

{

int temp = a->value;

a->value = b->value;

b->value = temp;

}

void sort(struct Node *start)

{

int swapped, i;

struct Node *ptr1;

struct Node *lptr = NULL;

/* Checking for empty list */

if (start == NULL)

return;

do

{

swapped = 0;

ptr1 = start;

while (ptr1->next != lptr)

{

if (ptr1->value > ptr1->next->value)

{

swap(ptr1, ptr1->next);

swapped = 1;

}

ptr1 = ptr1->next;

}

lptr = ptr1;

}

while (swapped);

}

int main()

{

struct Node* head = NULL;

FILE *fs;

    char ch, buffer[32];

    int i = 0, arr[100], j = 0;

    

    // Openning the file with file handler as fs

    fs = fopen("ages.txt", "r");

    // Read the file unless the file encounters an EOF

    while(1){

        // Reads the character where the seeker is currently

        ch = fgetc(fs);

        // If EOF is encountered then break out of the while loop

        if(ch == EOF){

            break;

        }

        //skipping the space character

        else if(ch == ' '){

            // Converting the content of the buffer into

            // an array position

            arr[j] = atoi(buffer);

            // Increamenting the array position

            j++;

            bzero(buffer, 32);

            i = 0;

            // then continue

            continue;

        }

        else{

            // reads the current character in the buffer

            buffer[i] = ch;

            i++;

        }

    }

    // printing out all the elements that are stored in the

    // array of integers

    for(i = 0; i < j; i++){

        printf("%d ", arr[i]);

    }

printf("\n\n");

for(int i=0; i<j; i++)

{

insert_in_end(&head,arr[i]);

}

printf("List of ages:\n");

display(head);

insert_in_front(&head,18);

printf("\nList after inserting 18 in front:\n");

display(head);

insert_in_end(&head,23);

printf("\nList after inserting 23 in end:\n");

display(head);

insert_after(&head,24,25);

printf("\nList after inserting 25 after 24:\n");

display(head);

printf("\nAverage age:%f\n",average_age(head));

sort(head);

printf("\nList after sorting in ascending order:\n");

display(head);

printf("\nNo. of people of age 18 or greater: %d",greater_than(head,18));

return 0;

}