feat: add "Sets" solution

Author: guilhermedom

the_captains_room.py

@@ -0,0 +1,11 @@
+K = int(input())
+
+tourists = input().split()
+single = set()
+group = set()
+for tourist in tourists:
+    if tourist not in single:
+        single.add(tourist)
+    else:
+        group.add(tourist)
+print(single.difference(group).pop())