Update insert-delete-getrandom-o1-duplicates-allowed.cpp

Author: kamyu104

C++/insert-delete-getrandom-o1-duplicates-allowed.cpp

@@ -12,7 +12,7 @@ class RandomizedCollection {
     bool insert(int val) {
         bool has = used_.count(val);
 
-        list_.emplace_back(val);
+        list_.emplace_back(val, used_[val].size());
         used_[val].emplace_back(list_.size() - 1);
 
         return !has; 
@@ -24,7 +24,7 @@ class RandomizedCollection {
             return false;
         }
 
-        used_[list_.back()].back() = used_[val].back();
+        used_[list_.back().first][list_.back().second] = used_[val].back();
         swap(list_[used_[val].back()], list_.back());
 
         used_[val].pop_back();
@@ -38,61 +38,14 @@ class RandomizedCollection {
 
     /** Get a random element from the collection. */
     int getRandom() {
-        return list_[rand() % list_.size()];
+        return list_[rand() % list_.size()].first;
     }
 
 private:
-    vector<int> list_;
+    vector<pair<int, int>> list_;
     unordered_map<int, vector<int>> used_;
 };
 
-
-// Time:  O(1)
-// Space: O(n)
-class RandomizedCollection2 {
-public:
-    /** Initialize your data structure here. */
-    RandomizedCollection2() {
-        
-    }
-    
-    /** Inserts a value to the collection. Returns true if the collection did not already contain the specified element. */
-    bool insert(int val) {
-        bool has = used_.count(val);
-
-        list_.emplace_back(val);
-        used_.emplace(val, list_.size() - 1);
-
-        return !has; 
-    }
-    
-    /** Removes a value from the collection. Returns true if the collection contained the specified element. */
-    bool remove(int val) {
-        if (!used_.count(val)) {
-            return false;
-        }
-
-        auto it_to_delete = used_.find(val);
-        auto it_to_back = used_.find(list_.back());
-        it_to_back->second = it_to_delete->second;
-        swap(list_[it_to_delete->second], list_.back());
-
-        used_.erase(it_to_delete);
-        list_.pop_back();
-
-        return true;  
-    }
-    
-    /** Get a random element from the collection. */
-    int getRandom() {
-        return list_[rand() % list_.size()];
-    }
-
-private:
-    vector<int> list_;
-    unordered_multimap<int, int> used_;
-};
-
 /**
  * Your RandomizedCollection object will be instantiated and called as such:
  * RandomizedCollection obj = new RandomizedCollection();