HACKERRANK SOLUTION : HANDSHAKE

import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;
import java.util.regex.*;

public class Solution {

static int handshake(int n) {
int x = (n*(n-1))/2;
return x;

}

private static final Scanner scanner = new Scanner(System.in);

public static void main(String[] args) throws IOException {
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv(“OUTPUT_PATH”)));

int t = Integer.parseInt(scanner.nextLine().trim());

for (int tItr = 0; tItr < t; tItr++) {
int n = Integer.parseInt(scanner.nextLine().trim());

int result = handshake(n);

bufferedWriter.write(String.valueOf(result));
bufferedWriter.newLine();
}

bufferedWriter.close();
}
}