Add G-Set (Grow-only Set) (#4975)

src/main/java/com/thealgorithms/datastructures/crdt/GSet.java

@@ -0,0 +1,65 @@
+package com.thealgorithms.datastructures.crdt;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * GSet (Grow-only Set) is a state-based CRDT (Conflict-free Replicated Data Type)
+ * that allows only the addition of elements and ensures that once an element is added,
+ * it cannot be removed. The merge operation of two G-Sets is their union.
+ * This implementation supports adding elements, looking up elements, comparing with other G-Sets,
+ * and merging with another G-Set to create a new G-Set containing all unique elements from both sets.
+ * (https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type)
+ *
+ * @author itakurah (Niklas Hoefflin) (https://github.com/itakurah)
+ */
+
+public class GSet<T> {
+    private final Set<T> elements;
+
+    /**
+     * Constructs an empty G-Set.
+     */
+    public GSet() {
+        this.elements = new HashSet<>();
+    }
+
+    /**
+     * Adds an element to the G-Set.
+     *
+     * @param e the element to be added
+     */
+    public void addElement(T e) {
+        elements.add(e);
+    }
+
+    /**
+     * Checks if the given element is present in the G-Set.
+     *
+     * @param e the element to be checked
+     * @return true if the element is present, false otherwise
+     */
+    public boolean lookup(T e) {
+        return elements.contains(e);
+    }
+
+    /**
+     * Compares the G-Set with another G-Set to check if it is a subset.
+     *
+     * @param other the other G-Set to compare with
+     * @return true if the current G-Set is a subset of the other, false otherwise
+     */
+    public boolean compare(GSet<T> other) {
+        return elements.containsAll(other.elements);
+    }
+
+    /**
+     * Merges the current G-Set with another G-Set, creating a new G-Set
+     * containing all unique elements from both sets.
+     *
+     * @param other the G-Set to merge with
+     */
+    public void merge(GSet<T> other) {
+        elements.addAll(other.elements);
+    }
+}