Create 432. All O`one Data Structure (#599)

Author: Chayandas07

432. All O`one Data Structure

@@ -0,0 +1,40 @@
+class AllOne {
+public:
+    unordered_map<string,int> count;
+    set<pair<int,string>> se;
+    AllOne() {
+        count.clear();
+    }
+
+    void inc(string key) {
+        int n = count[key];
+        count[key]++;
+        se.erase({n,key});
+        se.insert({n+1,key});
+    }
+    void dec(string key) {
+        int n = count[key];
+        count[key]--;
+        se.erase({n,key});
+        if(count[key] > 0) se.insert({n-1,key});
+    }
+    
+    string getMaxKey() {
+        if(!se.empty()) return se.rbegin()->second;
+        return "";
+    }
+    
+    string getMinKey() {
+        if(!se.empty()) return se.begin()->second;
+        return "";
+    }
+};
+
+/**
+ * Your AllOne object will be instantiated and called as such:
+ * AllOne* obj = new AllOne();
+ * obj->inc(key);
+ * obj->dec(key);
+ * string param_3 = obj->getMaxKey();
+ * string param_4 = obj->getMinKey();
+ */