Add C++ solution of problem #2349

Author: Cuda-Chen

2349/solution.cpp

@@ -0,0 +1,37 @@
+class NumberContainers {
+public:
+    NumberContainers() {
+        
+    }
+    
+    void change(int index, int number) {
+        if(!m.count(index)) {
+            m[index] = number;
+            mm[number].insert(index);
+            return;
+        }
+
+        int num = m[index];
+        mm[num].erase(index);
+        m[index] = number;
+        mm[number].insert(index);
+    }
+    
+    int find(int number) {
+        if(!mm.count(number) || mm[number].size() < 1)
+            return -1;
+        
+        return *(mm[number].begin());
+    }
+
+private:
+    unordered_map<int, int> m; // {idx, num}
+    unordered_map<int, set<int>> mm; // {num, idxs (sorted)}
+};
+
+/**
+ * Your NumberContainers object will be instantiated and called as such:
+ * NumberContainers* obj = new NumberContainers();
+ * obj->change(index,number);
+ * int param_2 = obj->find(number);
+ */