Given an array find the First duplicate element

Mahalasa Kini

2.1k

Given an array {1, 2, 3, 1, 5, 6,} the output should be
{1}

public void FirstRepeatingCahrecter(int[] arr){
int min=-1;
HashSet hset = new HashSet();
for(int i=arr.Length-1;i>0;i—){
if(hset.Contains(arr[i]))
min=i;
else
hset.add(arr[i]);
}
if(min!=-1){
Console.WriteLine(“The first repeating charecter is:”+ arr[min]);
}else
Console.WriteLine(“There is not repeating charecter in the array”);
}

var duplicates = arr.GroupBy(x => x).Select(x => x.Count() > 1);
return duplicates.First().key;

Sandip Kumar

string[] qwerty = { “Z”, “A”, “C”, “H”, “F”, “V”, “F”, “H”, “A” };

HashSet NoRepeat = new ();
string? first_repeat = null;
foreach (var item in qwerty)
{
if(!NoRepeat.Add(item))
{
first_repeat = item;
break;
}
}
Console.WriteLine(first_repeat);

Jair Archbold

var duplicates = arr.GroupBy(x => x).Where(x => x.Count() });
return duplicates.First().key;

Sandip Kumar

var duplicates = arr.GroupBy(x => x).Select(x => new { key = x.Key, val = x.Count() });
return duplicates.First().key;

Imogen Harden