'InsertionSort'ing a linked list

Posted on 1998-10-23
Medium Priority
Last Modified: 2011-09-20
Does anyone have code for Sorting a linked list using InsertionSort? Sorting by file size, date/time and then if necessary ID.  Without allocating any additional memory.  URGENT.  Bonus: if you determine the theoretical runtime.
Question by:stuckart

Expert Comment

ID: 1253772
sounds like homework to  me. You should try this yourself and then  ask on the parts you are having probs with.

Author Comment

ID: 1253773
This is not a homework question.  I am trying to teach myself.  It is easiest for me to learn by example.  The part that is hardest for me is the swapping of the pointers.
LVL 85

Expert Comment

ID: 1253774
what have you tried?
Identify and Prevent Potential Cyber-threats

Become the white hat who helps safeguard our interconnected world. Transform your career future by earning your MS in Cybersecurity. WGU’s MSCSIA degree program was designed in collaboration with national intelligence organizations and IT industry leaders.


Author Comment

ID: 1253775
Have in mind that I don't quite understand pointers that well.

void InsertionSort (Node *pHead)
    Node *pCur = *pHead, *pTemp = *pHead;
    while( pCur)      <------   don't know what to put here, want to check if pCur is valid
         pCur  =  pCur->pNext;
         while( pTemp->value > pCur->value)
              swap them here.  Not sure how to move the pointers to do this.

In my Data structure I have   File, Date, ID  they are incremented by 1.
I'll put the exact code here, once my e-mail provider gets back online.  Figures huh.


LVL 12

Accepted Solution

rwilson032697 earned 400 total points
ID: 1253776
Your code is pretty much there. The while (pCur) is fine as long as pCur is set to NULL when it runs into the end of the list.

Instead of the inner while do this for the insertion:

        if( pTemp->value > pCur->value)
           pTemp->nNext = pCur->pNext;
           pCur->pNext = pTemp;

In terms of theoretical runtime this will be O(n squared). If you had used an array it would have been O(n log n).

To swap two pointers do this:

Node *SwapTemp = SecondNode;
SecondNode = FirstNode;
FirstNode = SwapTemp;


LVL 12

Expert Comment

ID: 1253777
Just a wee note: The O(n log n) for an array assumes you use a binary search to locate the insertion positon - the overhead of the actual array insertion operation is ignored.

Author Comment

ID: 1253778
Thank you very much.  I actually had it almost exactly like you said, but I didn't have the *'s in the right place.  Thank you again,

Jerry Stuckart


Featured Post

KuppingerCole Reviews AlgoSec in Executive Report

Leading analyst firm, KuppingerCole reviews AlgoSec's Security Policy Management Solution, and the security challenges faced by companies today in their Executive View report.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This is a short and sweet, but (hopefully) to the point article. There seems to be some fundamental misunderstanding about the function prototype for the "main" function in C and C++, more specifically what type this function should return. I see so…
There's never been a better time to become a computer scientist. Employment growth in the field is expected to reach 22% overall by 2020, and if you want to get in on the action, it’s a good idea to think about at least minoring in computer science …
The goal of this video is to provide viewers with basic examples to understand recursion in the C programming language.
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use while-loops in the C programming language.
Suggested Courses

601 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question