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Find the count of distinct elementn in the given array in O(n) time .
We can use HashSet in Java to find the count of distinct element.
import java.util.*;
class Codechef {
public static void main(String args[]){
// Scanner for input
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
// array of size n
int arr[] = new int[n];
for(int i = 0 ; i < n ; i++){
arr[i] = sc.nextInt();
}
HashSet set = new HashSet <>();
// for each loop
for(int x : arr){
set.add(x);
}
// count of distinct elements in array
System.out.println(set.size());
}
}