Using vector and map

Author: gs146

Insert Delete GetRandom O(1)

@@ -0,0 +1,62 @@
+class RandomizedSet {
+public:
+    /** Initialize your data structure here. */
+    vector<int> v;
+    
+    map<int, int> m;
+    
+    RandomizedSet() {
+        srand(time(nullptr));
+    }
+    
+    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
+    bool insert(int val) 
+    {
+        
+        if(m.count(val))
+            return false;
+        
+       int index = v.size(); 
+        v.push_back(val); 
+              
+        // and hashmap also 
+        m[val] = index;
+        // m.insert(std::pair<int,int>(val, index)); 
+        return true;
+    }
+    
+    /** Removes a value from the set. Returns true if the set contained the specified element. */
+    bool remove(int val) 
+    {
+        
+        if(!m.count(val))
+            return false;
+        
+        int idx = m[val];
+        int last = v.back();
+        if(last!=val)
+        {
+            v[idx] = last;
+            m[last] = idx;
+        }
+        m.erase(val);
+        v.pop_back();
+        return true;
+    }
+    
+    /** Get a random element from the set. */
+    int getRandom() 
+    {
+        int random_idx = rand() % v.size();
+        return v[random_idx];
+        // return v[rand()%v.size()];
+    }
+};
+
+/**
+ * Your RandomizedSet object will be instantiated and called as such:
+ * RandomizedSet* obj = new RandomizedSet();
+ * bool param_1 = obj->insert(val);
+ * bool param_2 = obj->remove(val);
+ * int param_3 = obj->getRandom();
+ */