Create 380 Insert delete get random O(1).cpp

Author: Meghak1

380 Insert delete get random O(1).cpp

@@ -0,0 +1,38 @@
+class RandomizedSet {
+    vector<int> elements;
+    unordered_map<int,int> val_to_index;
+
+public:
+    
+  RandomizedSet() {
+  }
+
+  bool contains(int val) {
+    return val_to_index.find(val)!=val_to_index.end();
+  }
+
+  bool insert(int val) {
+    if (contains(val))
+       return false;
+
+    elements.push_back(val);
+    val_to_index[val]=elements.size()-1;
+    return true;
+  }
+
+  bool remove(int val) {
+    if (!contains(val))
+       return false;
+
+    auto it=val_to_index.find(val);
+    elements[it->second]=elements.back();
+    elements.pop_back();                           
+    val_to_index[elements[it->second]]=it->second;
+    val_to_index.erase(val);
+     return true;
+  }
+
+ int getRandom() {
+    return elements[rand()%elements.size()];
+    }
+};