add time value map

cpp/time_value_map.cpp

@@ -0,0 +1,58 @@
+#include <iostream>
+#include <vector>
+#include <map>
+
+template <typename K, typename V>
+class TimeValueMap
+{
+public:
+    void set(const K& key, const V& value, int timestamp)
+    {
+        _map[key][timestamp] = value;
+    }
+
+    V get(const K& key, int timestamp)
+    {
+        const auto values = _map.find(key);
+        if (values == _map.end())
+        {
+            return V();
+        }
+
+        const auto& values_map = values->second;
+        auto value = values_map.lower_bound(timestamp);
+        if (value == values_map.end())
+        {
+            if (timestamp > values_map.rbegin()->first)
+            {
+                return values_map.rbegin()->second;
+            }
+
+            return V();
+        }
+
+        if (value->first != timestamp)
+        {
+            if (value == values_map.begin())
+            {
+                return V();
+            }
+
+            value--;
+        }
+
+        return value->second;
+    }
+
+private:
+    std::map<K, std::map<int, V>> _map;
+};
+
+int main()
+{
+    TimeValueMap<std::string, std::string> map;
+    //map.set("a", "1", 1);
+    map.set("a", "2", 2);
+    map.set("a", "5", 5);
+    std::cout << map.get("a", 10) << '\n';
+}