Time: 413 ms (14.83%), Space: 96.9 MB (83.21%) - LeetHub

insert-delete-getrandom-o1/insert-delete-getrandom-o1.cpp

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+class RandomizedSet {
+public:
+    unordered_set<int> s;
+    RandomizedSet() {
+        s.clear();
+    }
+
+    bool insert(int val) {
+        if(s.count(val))
+            return false;
+        s.insert(val);
+        return true;
+    }
+
+    bool remove(int val) {
+        if(s.count(val)) {
+            s.erase(val);
+            return true;
+        }
+        return false;
+    }
+
+    int getRandom() {
+        int n = s.size();
+        int randNo = rand()%n;
+        auto itr = s.begin();
+        advance(itr, randNo);
+        return *itr;
+    }
+};
+
+/**
+ * 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();
+ */