Finding the nth largest in an int array

Question

I need to be able to find the nth largest numbers in an int array, I already have a linq statement that returns something but it's not passing the used cases that are set up. The array is:

var numbers = new[] { 5, 7, 5, 3, 6, 7, 9 };

My code is:

  var result = numbers.GroupBy(x => x)
                .OrderByDescending(group => group.Key)
                .SkipWhile(group =>
                {
                    n -= group.Count();
                    return n > 0;
                })
                .First()
                .ToArray();

I don't understand why I'm not getting the expected results?

  result[0] == 9
  result[1] == 7

For what `n`? Anyway, you're skipping `n` first elements, so for any `n > 0` you will not get `9`. — zerkms, Apr 22 '16 at 00:31
Possible duplicate of [How can we find the i'th greatest element of the array?](http://stackoverflow.com/questions/3124257/how-can-we-find-the-ith-greatest-element-of-the-array) — Mostafiz, Apr 22 '16 at 03:52

score 3 · Accepted Answer · answered Apr 22 '16 at 01:21

You can just use Take() to get the n largest items after the collection is ordered descending :

var result = numbers.GroupBy(x => x)
                    .OrderByDescending(group => group.Key)
                    .Take(n)
                    .Select(group => group.Key)
                    .ToArray();

dotnetfiddle demo

or use Skip(n-1).Take(1) if you mean to get only the nth item instead.

Finding the nth largest in an int array

1 Answers1