CODEWITHSUNDEEP
javaalgorithm
Mohamed Salad
Mohamed Salad

Reputation: 179

ComparisonCountingSort pseudocode difficulty

This algorithm given to us in class:

enter image description here

I am having trouble in my attempts to determine the output when the input is an array A[60,35,81,98,14,47].

I wanted to get used to the pseudocode syntax, so I tried to convert this to Java syntax, but the resulting program won't show a result. This is my converted code:

public class Driver
{
    public static void main(String[] args)
    {
        int[] test = {60, 35, 81, 98, 14, 47}; 
        int[] converse = new int[6];

        converse = countSort(test);

        for(int i : converse)
        {
            System.out.println(converse[i]);
        }
    }

    public static int[] countSort(int[] a)
    {
        int[] s = new int[6];
        int[] count = new int[6];
        int n = a.length + 1;

        for(int i = 0; i < (n-1);)
        {
            count[i] = 0;
        }

        for(int i = 0; i < (n-2);)
        {
            for(int j = (i+1); i < (n-1);)
            {
                if(a[i] < a[j])
                {
                    count[j] = count[j]+1;//What
                }
                else
                {
                    count[i] = count[i]+1;
                }
            }
        }

        for (int i = 0; i < (n-1);)
        {
            s[count[i]] = a[i];
        }

        return s;
    }
}

Upvotes: 0

Views: 324

Answers (2)

maxkra
maxkra

Reputation: 87

  1. Your array test is never used.
  2. In your for loops, i never gets incremented. It will loop infinetely.
  3. Instead of n = a.length+1; just use n = a.length. it makes your code easier to read. You then also have to check all your loops.

When you are running the code with a testset larger or less than 6 integer values your code wont run correctly or even fail with an ArrayOutOfBounds Exception, as you allocate the arrays s and count for only 6 values. Try int[] count = new int[a.length]; instead of int[] count = new int[a.length];. The same for s.

Upvotes: 1

Damien O&#39;Reilly
Damien O&#39;Reilly

Reputation: 992

int[] test = {60,35,81,98,14,47}; is never used.

Did you mean to pass test into countSort? and also do something with it's result.

While I haven't looked at the algorithm really, there is something else wrong here:

int n = a.length + 1; for (int i = 0; i < (n - 1);) { count[i] = 0; }

This will loop indefinatetly. i never incerements.

Upvotes: 3

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