从文件c ++导入并插入排序

Question

I am working on a project that needs to do this:

In C++ create a class that is a doubly linked list of integers.

This class should have the following: -Normal insertion functions(push_back, push_front) -Normal deletion functions(pop_back, pop_front) -3 Sorting functions -Insertion Sort -Merge Sort -Bubble Sort

The sorting methods should print out the processing time(down to either micro or milliseconds), and the sort used(eg after bubble sort finishes, Bubble Sort- 100ms).

Create a program that read's in a bunch of numbers from file and creates your linked list(create three lists to for each run). The program should then sort with each method. Show results for three runs, one with a list of 100000 numbers, one with 10000, one with 1000 numbers.

I am stuck on trying to import my first file (file1.txt) that has 100000 integers and saving them into my doubly linked list. Any advice on how to do that would be so great. Next, I am trying to work on the insertion sort algorithm, and what I have so far is insertion sort for an array and not doubly linked list. If you could scan through my code and give me any advice that would be great. I have never coded in C++, only in java, and this assignment is challenging for me!

#include<iostream>
//for time elapsed
#include <chrono>

using namespace std;
template <class T>
class doublylinkedlist
{
private :
    struct node
    {
        T data;
        node *prev;
        node *next;
    };
    node *head;
    node *tail;
public :
    doublylinkedlist()
    {
        head=tail=NULL;
    }
    void createlist(T[] , int);
    void pushfirst(T);
    void pushlast(T);
    void pushafter(T,T);
    void pop(T);
    void displayforward();
    void displaybackward();
};
//creating doubly linked list
template<class T>
void doublylinkedlist<T>::createlist(T x[], int n) //n = size 
{
    node *q;
    node *p=new node;   //create first node
    p->data=x[0];
    p->next=NULL;
    p->prev=NULL;
    for(int i=1;i<n;i++)
    {
        q=p;               
        p=p->next=new node;
        p->data=x[i];
        p->next=NULL;
        p->prev=q;
    }
    tail=p;
}
// Inserting new node at start of doubly linked list
template<class T>
void doublylinkedlist<T>::pushfirst(T item)
{
    node *p=new node;
    p->data=item;
    p->prev=NULL;
    head->prev=p;
}
//Inserting new node at last of Double Linkedlist
template<class T>
void doublylinkedlist<T>::pushlast(T item)
{
    node *p=new node;
    p->data=item;
    p->prev=tail;
    p->next=NULL;
    tail=p;
}

//deleting item from double linked list
template<class T>
void doublylinkedlist<T>::pop(T item)
{
    if(head==NULL)
    {
        cout<<"This list is empty!"<<endl;
        return;
    }
    if(head->data==item)
    {
        head=head->next;
        head->prev=NULL;
        return;
    }
    if(tail->data==item)
    {
        tail=tail->prev;
        tail->next=NULL;
        return;
    }
    node *p=head->next;
    while(p!=NULL)
    {
        if(p->data==item)
            break;
        p=p->next;
    }
    if(p==NULL)
    {
        cout<<item<<"not found "<<endl;
        return;
    }
    (p->prev)->next=p->next;
    (p->next)->prev=p->prev;
    return;
}
//displaying list elements in forward direction
template<class T>
void doublylinkedlist<T>::displayforward()
{
    node *p=head;
    cout<<"\n Doubly linked list (Forward)";
    while(p!=NULL)
    {
        cout<<p->data<<"";
        p=p->next;
    }
}
//displaying list elements in reverse direction
template<class T>
void doublylinkedlist<T>::displaybackward()
{
    node *p=tail;
    cout<<"\n Doubly linked list (Backward)";
    while(p!=NULL)
    {
        cout<<p->data<<"";
        p=p->prev;
    }
}
//insertion sort function
void doublylinkedlist<T>::insertionSort(T x[], int n) 
{
 auto beg = std::chrono::high_resolution_clock::now();

    int i, j ,tmp;
    for (i = 1; i < n; i++) 
    {
       j = i;
       while (j > 0 && x[j - 1] > x[j]) 
       {
       tmp = x[j];
       x[j] = x[j - 1];
       x[j - 1] = tmp;
       j--;
       }
    printArray(x,5);
    }

    auto end = std::chrono::high_resolution_clock::now();
    std::cout << std::chrono::duration_cast<std::chrono::milliseconds>(end - beg).count() << std::endl;

    std::cin.get();
    return 0;
}


int main()
{

  ifstream myfile ("file1.txt");
  if (myfile.is_open())
  {
    //i need to insert the file into the doubly linked list here.
    //file.txt is has 100000 integers 
    doublylinkedlist<int> firstList;
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
    //replace this with input from file

    //10000 numbers
    doublylinkedlist<int> secondList;
    //1000 numbers 
    doublylinkedlist<int> thirdList;

    //example of what to run 
    firstList.createlist(x,2);
    firstList.pushfirst(22);
    firstList.pushlast(55);
    firstList.pushafter(66,33);
    firstList.pop(22);
    firstList.pop(55);
    firstList.pop(66);
    return 0;
}

Answer 1

After successfully opening the file, you need to add a loop doing:

read a number from the file into temp variable
firstList.pushlast(temp)

Regarding sorting, I believe you are expected to move the nodes in the list (instead of copying values between the nodes - the way its done in array) to make the list sorted.