Question

In this part, you have to implement a linked list that maintains a list of integers in sorted order. Thus, if the list contains 2, 5 and 8, then 1 will be inserted at the start of the list, 3 will be inserted between 2 and 5 and 10 will be inserted at the end. The list can contain duplicate elements. 1 Input format: This program takes a le name as an argument from the command line. The le is either blank or contains successive lines of input. Each line contains a character, either `i' or `d', followed by a tab character and then an integer. For each of the lines that starts with `i', your program should insert that number in the linked list in sorted order. If it is already there, your program can insert it before or after the existing entry. If the line starts with a `d', your program should delete the rst value if it is present in the linked list. If there are duplicates your program must delete just the rst occurrence of the value. Your program should silently ignore the line if the requested value is not present in the linked list.

Answer 1

Answer:

#include <stdio.h>   // header file

#include <stdlib.h>

struct node{    //define structure "node"

int data;

struct node* next;    // object

};

struct node* add(struct node* head, int num);

struct node* delete(struct node* head, int num);

void print(struct node* head);

int size(struct node* head);

int main(int argc, char* argv[]){

FILE *fp = NULL;

struct node* head = NULL;

int num;

char command;

if(argc != 2){

printf("Please provide input filename as a command line argument\n");

return 1;

}

fp = fopen(argv[1], "r");

if(fp == NULL){

printf("error\n");

return 1;

}

fscanf(fp, "%c %d", &command, &num);

while(!feof(fp)){

if(command == 'i')

head = add(head, num);

else if(command == 'd')

head = delete(head, num);

fscanf(fp, "%c %d", &command, &num);

}

fclose(fp);

printf("%d\n",size(head));

print(head);

}

struct node* add(struct node* head, int num){

struct node* prev = NULL;

struct node* curr = head;

struct node* n = (struct node*) malloc(sizeof(struct node));

n->data = num;

n->next = NULL;

while(curr != NULL){

if(num < curr->data) //found a place to insert

break;

else if(num == curr->data) //duplicate

return head;

prev = curr;

curr = curr->next;

}

n->next = curr;

if(prev != NULL)

prev->next = n;

else

head = n;

return head;

}

struct node* delete(struct node* head, int num){

struct node* prev = NULL;

struct node* curr = head;

while(curr != NULL){

if(num < curr->data)

return head;

else if(num == curr->data)

break;

prev = curr;

curr = curr->next;

}

if(curr == NULL) //did not find

return head;

if(prev == NULL) //remove 1st node

head = curr->next;

else

prev->next = curr->next;

free(curr);

return head;

}

void print(struct node* head)

{

struct node* curr = head;

if(head != NULL){

printf("%d", curr->data);

curr = curr->next;

while(curr != NULL){

printf("\t%d", curr->data);

curr = curr->next;

}

}

printf("\n");

}

int size(struct node* head){

struct node* curr = head;

int count = 0;

while(curr != NULL){

count++;

curr = curr->next;

}

return count;

}

Output:

Provide input filename as a command-line argument

Test2 sg$ ./.s.out in.txt

2  5  8

1  2  3  5  10

Test2 sg$  

Explanation:

we create a link list of integer in sorted order then if we input as 2  5  8, then 1  insert at the starting of the list and 3 in middle of 2 and 5 and 10 is inserted at the last.