HashSet --Design 1

HashSet.java

@@ -0,0 +1,49 @@
+// Time Complexity : O(n) for add, remove, and contains — each linearly scans the ArrayList
+// Space Complexity : O(n) — stores up to n unique keys in the ArrayList
+// Did this code successfully run on Leetcode : Yes
+// Any problem you faced while coding this : None
+
+class MyHashSet {
+    ArrayList<Integer> hashSet = new ArrayList<>();
+
+    public MyHashSet() {
+
+    }
+
+    public void add(int key) {
+        boolean repeated = false;
+        for(int i=0;i < hashSet.size(); i++){
+            if(hashSet.get(i)==key){
+                repeated = true;
+            }
+        }
+        if(repeated== false){
+            hashSet.add(key);
+        }
+    }
+
+    public void remove(int key) {
+        for(int i=0;i<hashSet.size();i++){
+            if(hashSet.get(i)==key){
+                 hashSet.remove(Integer.valueOf(key));
+            }
+        }
+    }
+
+    public boolean contains(int key) {
+         for(int i=0;i<hashSet.size();i++){
+            if(hashSet.get(i)==key){
+                 return true;
+            }
+        }
+        return false;
+    }
+}
+
+/**
+ * Your MyHashSet object will be instantiated and called as such:
+ * MyHashSet obj = new MyHashSet();
+ * obj.add(key);
+ * obj.remove(key);
+ * boolean param_3 = obj.contains(key);
+ */