Java Hashset Hackerrank Solution For Explanation Watch Video: Sample Input 5 john tom john mary john tom mary anna mary anna Sample Output 1 2 2 3 3 Code: import java.io.*; import java.util.*; import java.text.*; import java.math.*; import java.util.regex.*; public class Solution { public static void main(String[] args) { Scanner s = new Scanner(System.in); int t = s.nextInt(); String [] pair_left = new String[t]; String [] pair_right = new String[t]; for ( int i = 0 ; i < t; ...