Added 26 solutions

Java/Data Structures/Java Hashset/Solution.java

@@ -0,0 +1,31 @@
+//     Author: Rodney Shaghoulian
+//     Github: github.com/rshaghoulian
+// HackerRank: hackerrank.com/rshaghoulian
+
+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; i++) {
+            pair_left[i] = s.next();
+            pair_right[i] = s.next();
+        }
+        s.close();
+
+        HashSet<String> set = new HashSet<>(t);
+        for (int i = 0; i < t; i++) {
+            set.add(pair_left[i] + " " + pair_right[i]);
+            System.out.println(set.size());
+        }
+    }
+}