JavaHashset.java

// https://www.hackerrank.com/challenges/java-hashset/problem

import java.util.HashSet;
import java.util.Objects;
import java.util.Scanner;
import java.util.Set;

public class JavaHashset {
 public static void main(String[] args) {
 Scanner scanner = new Scanner(System.in);
 int queries = scanner.nextInt();
 Set<Pair> set = new HashSet<>();

 while (queries-- > 0) {
 String first = scanner.next();
 String second = scanner.next();
 Pair pair = new Pair(first, second);
 set.add(pair);
 System.out.println(set.size());
 }
 }

 private static class Pair {
 private final String first;
 private final String second;

 Pair(String first, String second) {
 this.first = first;
 this.second = second;
 }

 @Override
 public boolean equals(Object o) {
 if (this == o) return true;
 if (o == null || getClass() != o.getClass()) return false;
 Pair pair = (Pair) o;
 return Objects.equals(first, pair.first) &&
 Objects.equals(second, pair.second);
 }

 @Override
 public int hashCode() {
 return Objects.hash(first, second);
 }
 }
}