Merge pull request #84 from Weltenbummler397/exercism-sync/eeeb011ef9718021

[Sync Iteration] java/gotta-snatch-em-all/1

solutions/java/gotta-snatch-em-all/1/src/main/java/GottaSnatchEmAll.java

@@ -0,0 +1,47 @@
+import java.util.List;
+import java.util.Set;
+
+class GottaSnatchEmAll {
+
+    static Set<String> newCollection(List<String> cards) {
+        return Set.copyOf(cards);
+    }
+
+    static boolean addCard(String card, Set<String> collection) {
+        return collection.add(card);
+    }
+
+    static boolean canTrade(Set<String> myCollection, Set<String> theirCollection) {
+        boolean a = !myCollection.containsAll(theirCollection);
+        boolean b = !theirCollection.containsAll(myCollection);
+        return a && b;
+    }
+
+    static Set<String> commonCards(List<Set<String>> collections) {
+        if (collections == null || collections.isEmpty()) {
+            return Set.of();
+        }
+
+        Set<String> common = Set.copyOf(collections.get(0));
+
+        for (int i = 1; i < collections.size(); i++) {
+            common = common.stream()
+                           .filter(collections.get(i)::contains)
+                           .collect(java.util.stream.Collectors.toUnmodifiableSet());
+        }
+
+        return common;
+    }
+
+     static Set<String> allCards(List<Set<String>> collections) {
+        List<String> cards = new java.util.ArrayList<>();
+        for (Set<String> set : collections) {
+            for (String card : set) {
+                if (!cards.contains(card)) {
+                    cards.add(card);
+                }
+            }
+        }
+        return Set.copyOf(cards);
+    }
+}