Question

5.8 Sort Linked List

Use mergersort to sort a linked list Do not use the following libraries: algorithm, cmath. Do not load the values into a vector and sort them. The sort must be done with a linked list
Example
Two lists 6->3->1->2->4->5 will return a list with 1->2->3->4->5->6.
Input
There will be no input read in anymore. Going forward use the hard-coded input on the template and ensure the program works. There will be one compare output test based on the hard-coded input. The rest of the tests will be unit tests.
Output
Print out the newly returned list. Just print out the integers separated by a space.

#include <iostream>

#include <vector>

// DO NOT MODIFY

struct Node {

    int val;

    Node * next;

    Node( int num ){

        val = num;

        next = nullptr;

    }

};

// DO NOT MODIFY

Node * createList( std::vector<int> & vec ){

    int i = 0;

    Node * head = new Node( vec[i++] );

    Node * runner = head;

    for( i; i < vec.size(); i++ ){

        Node * temp = new Node( vec[i] );

        runner->next = temp;

        runner = runner->next;

    }

    

    return head;

}

    Node* mergeTwoLists(Node* l1, Node* l2) {

        // Use your mergeTwoLists function from last week

    }

    

    Node * mergeSort( Node * head ){

        /* Follow merge sort. The tricky part is spliting the lists in half at each step correctly.

        If you are not confident, draw out how you could split each list in half till you hit a base case.

        */

    }

    

    

int main(){

   // Just concentrate on the function

   std::vector<int> values{ 6, 3, 1, 2, 4, 5};

   

   Node * list = createList( values );

   

   list = mergeSort( list );

   

   while( list ){

      std::cout << list->val << " ";

      list = list->next;

   }

Answer 1

Answer:-

code:

 #include <iostream>
#include <vector>
// DO NOT MODIFY
struct Node
{
    int val;
    Node * next;
    Node( int num )
    { val = num; 
    next = NULL; }
};
    // DO NOT MODIFY
Node * createList( std::vector<int> & vec )
{
    int i = 0; 
    Node * head = new Node( vec[i++] );
    Node * runner = head;
    for( i; i < vec.size(); i++ )
    {
        Node * temp = new Node( vec[i] );
        runner->next = temp;
        runner = runner->next;
    }
    return head;
}
Node* mergeTwoLists(Node* l1, Node* l2)
{
    // Use your mergeTwoLists function from last week
    struct Node* temp1=l1,*temp2=l2,*head,*temp,*hemp;       //temporary variables 
    /* for assigning head for new merged list */
    if(temp1->val<=temp2->val)
    { 
        temp=temp1->next;
        head=temp1;
        if(temp1!=NULL)
        temp1->next=NULL;
        temp1=temp;
    } 
    else
    {
        temp=temp2->next;
        head=temp2;
        if(temp2!=NULL) 
        temp2->next=NULL;
        temp2=temp;
    }
    hemp=head;        //storing new head in a temporary variable for iteration 
    /*upto here*/ 
    /*here merging rest of the list*/ 
    while(temp1!=NULL && temp2!=NULL )
    {
        if(temp1->val<temp2->val)
        {
            temp=temp1->next;
            hemp->next=temp1;
            if(temp1!=NULL)
            temp1->next=NULL;
            temp1=temp;
            hemp=hemp->next;
        }
        else
        {
            temp=temp2->next;
            hemp->next=temp2;
            if(temp2!=NULL)
            temp2->next=NULL;
            temp2=temp;
            hemp=hemp->next;
        }
    }
    while(temp1!=NULL)
    { 
        temp=temp1->next;
        hemp->next=temp1;
        if(temp1!=NULL)
        temp1->next=NULL;
        temp1=temp;
        hemp=hemp->next;
    }
    while(temp2!=NULL)
    {
        temp=temp2->next;
        hemp->next=temp2;
        if(temp2!=NULL)
        temp2->next=NULL;
        temp2=temp;
        hemp=hemp->next;
    } 
    return head;
}
Node * mergeSort( Node * head )
{
    /* Follow merge sort.
    The tricky part is spliting the lists in half at each step correctly
    . If you are not confident, draw out how you could split each list in half till you hit a base case. */
    if (head==NULL||head->next==NULL)
    return head;
    /* split the list by finding mid using slow& fast pointers*/
    struct Node *s=head;
    struct Node *f=head;
    struct Node *temp;
    while(1)
    {
        if(f->next==NULL||f->next->next==NULL)
        break;
        else
        {
            f=f->next->next;
            s=s->next;
        }
    }
    temp=s->next;
    s->next=NULL;
    /*upto here*/
    head = mergeSort(head);
    temp = mergeSort(temp);
    /* calling the merge function */
    Node* merged_head= mergeTwoLists(head,temp);
    return merged_head;
}
int main()
{
    // Just concentrate on the function
    std::vector<int> values{ 6, 3, 1, 2, 4, 5};
    Node * list = createList( values );
    list = mergeSort( list );
    while( list )
    {
        std::cout << list->val << " ";
        list = list->next;
    }
}

output:

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Run Debug Stop Share A Save {}Beautify Language C++ 14 @ main.cpp CO if(temp2!=NULL) temp 2->next=NULL; temp2=temp; hemp=hemp->next; while(temp1!=NULL) 600 OU WN 99 100 temp=temp 1 ->next; hemp->next=temp1; if(temp1!=NULL) temp 1->next=NULL; temp1=temp; hemp=hemp->next; 101 102 103 while(temp2!=NULL) 104 - 105 106 107 108 109 110 111 112 temp=temp 2 ->next; hemp->next=temp2; if(temp2!=NULL) temp 2 ->next=NULL; temp2=temp; hemp=hemp->next; return head; 113 114 115 input 1 2 3 4 5 6 ... Program finished with exit code o Press ENTER to exit console. Activate Windows Go to Settings to activate Windo