KAispread
diff --git a/‎src/data_structure/HashSet.java‎
Lines changed: 70 additions & 0 deletions b/‎src/data_structure/HashSet.java‎
Lines changed: 70 additions & 0 deletions
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+package data_structure;
+
+public class HashSet<V> {
+
+    private static final Object EMPTY_VALUE = new Object();
+
+    private final HashMap<V, Object> hashMap;
+
+    public HashSet() {
+        this.hashMap = new HashMap<>();
+    }
+
+    public void add(V value) {
+        hashMap.put(value, EMPTY_VALUE);
+    }
+
+    public boolean contains(V value) {
+        return hashMap.contains(value);
+    }
+
+    public boolean delete(V value) {
+        if (hashMap.contains(value)) {
+            hashMap.delete(value);
+            return true;
+        }
+        return false;
+    }
+
+    public int size() {
+        return hashMap.entrySet().size();
+    }
+
+    /*
+    * for test
+    * */
+    public void print() {
+        hashMap.entrySet().forEach(entry -> {
+            System.out.println("value : " + entry.getKey());
+        });
+    }
+
+    public static void main(String[] args) {
+        HashSet<String> stringSet = new HashSet<>();
+
+        stringSet.add("contents");
+        stringSet.add("valuable");
+        stringSet.add("mvp");
+        stringSet.add("claude");
+        stringSet.add("gpt");
+        stringSet.add("valuable");
+
+        stringSet.print();
+        System.out.println("size = " + stringSet.size());
+        System.out.println("--- cut ---");
+
+        stringSet.delete("valuable");
+        stringSet.delete("none value");
+
+        stringSet.print();
+        System.out.println("size = " + stringSet.size());
+        System.out.println("--- cut ---");
+
+        stringSet.add("valuable");
+        stringSet.add("none value");
+
+        stringSet.print();
+        System.out.println("size = " + stringSet.size());
+        System.out.println("--- cut ---");
+    }
+}