Thread: Integer Array Please help

Hi..

I have to create a code that will prompt the user to enter values for two int arrays. Each array is of length 5, with values such that 0 <= 'i' <= 99. Values entered for each array must be unique... The program will will compute the set intersection of the two arrays. That is, the program will display every value which the two arrays have in common.

For example, if array A = {5, 4, 3, 2, 1} and array B = {2, 4, 6, 8, 10} then their intersection is {2, 4}. If the two arrays have no common elements, the program should print a 'NULL SET' message. }

This is what I have created so far..

Code:

#include<stdio.h>
/* Function prints Intersection of arr1[] and arr2[]
   m is the number of elements in arr1[]
   n is the number of elements in arr2[] */
int print Intersection(int arr1[], int arr2[], int m, int n)
{
  int i = 0, j = 0;
  while(i < m && j < n)
  {
    if(arr1[i] < arr2[j])
      i++;
    else if(arr2[j] < arr1[i])
      j++;
    else  /* if arr1[i] == arr2[j] */
    {
      printf(" %d ", arr2[j++]);
      i++;
    }
  }
}

I cant quite figure out how to further represent the two arrays in my code. Can anyone please give me a hint or two? Am I on the right track? I have a very limited knowledge of C programming and a tutor was helping me before.. Unfortunately now that classes are over he doesnt come to our lab anymore. Thank you so much...

Where is the rest of your code? All programs must have a main().

Show more work and we'll gladly help you. For example, can you correctly load the data into arrays and print the data back out?

Actually, KBriggs, the original poster's solution is better than yours. Yes, the arrays need to be sorted.

See, sorting an array can be done in O(n log n). Then his algorithm is correct in O(n), which means a total of O(n + n log n).

Your solution compares everything, which is O(n^2).

His solution is better.


jj121: Your solution is perfect so far. So good that I have to doubt you did it yourself to be honest, if you have to ask the question whether it's good.

Right, I was assuming that they were not sorted. If they are sorted then his solution is indeed better. However, since there was no mention made of any such sorting, his solution will not work in general unless he does that elsewhere, something he is obviously not aware of given his example arrays.

I find that brute force is a good way to start learning, and you can refine things from there.

Huh!

Guess you put a lot of work in over the weekend.

Originally Posted by KBriggs

Right, I was assuming that they were not sorted. If they are sorted then his solution is indeed better. However, since there was no mention made of any such sorting, his solution will not work in general unless he does that elsewhere, something he is obviously not aware of given his example arrays.

I find that brute force is a good way to start learning, and you can refine things from there.

As I stated, sorting and then using this algorithm is faster (generally).
And yes, it's copied, my expectation was correct ;-).

Actually

I believe, EVOEx, that I explained myself in the first post. I did fear that someone would accuse me of plagiarism - which is why I mentioned a tutor has been helping me. My tutor helped me to right that code. If anyone is doubting me, I understand. I tried posting this in 2 other forums and working on it on my own but without someone explaining it to me, its kind of hard. You see, my father died right before classes began and things have been really hectic for me, as you could assume. I missed a lot of classes because of that and now, at the end of the semester, I am paying for it. I am now just trying not to fail this class that I had to take. In my culture it is tradition that you take the deceased's ashes to India so I will be leaving in 3 days for the entire summer, I have a very limited amount of time to complete this assignment. I dont feel that I owed you this explanation but maybe it can help you to understand my situation. No, I did not write that code on my own. Yes, I posted in two other forums, but when people accused me of plagiarizing there I didnt feel I had to explain my code/I gave up on trying to explain myself before I even tried to.

I have done all of my other homework assignments either by researching and hoping that I will eventually figure it out, or asking that tutor for help. That tutor is no longer available to me and this is all I have left. I hope that you will find it in your heart to understand.

Thank you..

This is really an assignment from class :-)
Any how I hope the problem was fixed.

Are you in my class Adnan?

Originally Posted by EVOEx

Actually, KBriggs, the original poster's solution is better than yours. Yes, the arrays need to be sorted.

See, sorting an array can be done in O(n log n). Then his algorithm is correct in O(n), which means a total of O(n + n log n).

Your solution compares everything, which is O(n^2).

His solution is better.

Not for the problem domain, which is defined as n=5. Or maybe it is, but big-O isn't going to tell you which approach is faster. And that's assuming faster is a useful way to evaluate "better" in this case.