Finding duplicate values in an array and outputing all of them

Question

So I have some working code for outputting duplicate values in an array, however it is always one short when it outputs them on the screen and I know it has to do with the following code, but I just can't put my finger on it. Please note I can't use any System.Array.

for (column = 0; column < WinningScores.Length -1 ; column++) 
{
    if (WinningScores[column] == WinningScores[column + 1]) 
    {
        duplicateScore = WinningScores[column];
        duplicateIndex = column;
        Console.Write("\n Competitor {0} is the Winner with a total of: {1}", 
                      duplicateIndex + 1, 
                      duplicateScore - totalSum);
    }
}

Hey! Can you please tell us for some sample values what is the output that you are getting and what is expected? It would be easier for us to understand the issue. — Alok Gupta
– Alok Gupta, Commented Apr 4, 2016 at 12:40
If it's always one short is it something to do with WinningScores.Length -1 ... should it just be WinningScores.Length ? — user964769
– user964769, Commented Apr 4, 2016 at 12:41
its like its missing the last value of the Array "WinningScores" — diam
– diam, Commented Apr 4, 2016 at 12:42
@Diam In your If condition, that would allow you to make a different action for the last repetition only. However, you'll want to do something else, you're not checking for duplicates here but for two consecutive values — Irwene
– Irwene, Commented Apr 4, 2016 at 12:49
"I can't use system.array". You really should tell us why we might have to tie our hands behind our backs to solve your problems. — spender
– spender, Commented Apr 4, 2016 at 12:52

Enigmativity · Accepted Answer · 2016-04-04 12:54:06Z

3

You could try using LINQ for this:

double[] WinningScores = new double[] { 4, 5, 3, 5 };

var duplicates =
    WinningScores
        .Select((score, index) => new { score, player = index + 1})
        .GroupBy(x => x.score, x => x.player)
        .Where(gxs => gxs.Count() > 1);

That gives me this result:

You can see that it picked up the duplicate score of 5 with players 2 & 4.

answered Apr 4, 2016 at 12:54

Enigmativity

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2 Comments

spender Over a year ago

I wonder if OP can't use System.Array whether linq might fall into the same category.

Enigmativity Over a year ago

@spender - probably, but he wasn't clear on that or why he couldn't use System.Array. It's still a nice answer and SO is for the community, not just the OP.

MNF · Accepted Answer · 2016-04-04 13:01:05Z

1

Your code looks for duplication in consécutive values. Try this code to output duplicate values in an array.

  for (column = 0; column < WinningScores.Length -1 ; column++) 
     {

        for (int cl= column + 1 ; cl < WinningScores.Length - 1 ; cl++)
            {
               if (WinningScores[column] == WinningScores[cl]) {


                        duplicateScore = WinningScores[column];
                        duplicateIndex = column;
                        Console.Write("\n Competitor {0} is the Winner with a total  of: {1}", duplicateIndex + 1, duplicateScore - totalSum);
              }
             }
         }

answered Apr 4, 2016 at 13:01

MNF

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Comments

drneel · Accepted Answer · 2016-04-04 13:23:36Z

0

//Starts loop through first element
for(int i = 0; i < arr.length, i++)

//starts at second element in array
for(int j = i + 1; k < arr.length, j++)

//double check my logic though, in a hurry at work so had to post this in a rush.

edited Apr 4, 2016 at 13:23

drneel

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answered Apr 4, 2016 at 13:05

JP Hochbaum

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