Merge pull request neetcode-gh#3123 from nkawaller/design-hash-set

Create 0705-design-hash-set.cpp

Author: MHamiid

cpp/0705-design-hashset.cpp

@@ -0,0 +1,25 @@
+// Time: O(n)
+// Space: O(n)
+
+class MyHashSet {
+public:
+    void add(int key) {
+        if (!contains(key)) {
+            hashSet.push_back(key);
+        }
+    }
+
+    void remove(int key) {
+        auto k = find(hashSet.begin(), hashSet.end(), key);
+        if (k != hashSet.end()) {
+            hashSet.erase(k);
+        }
+    }
+
+    bool contains(int key) {
+        return (find(hashSet.begin(), hashSet.end(), key) != hashSet.end());
+    }
+
+private:
+    vector<int> hashSet;
+};