ADD Time-Based-Key-Value-Store problem #52

Author: khaled-alselwady

Medium/time-based-key-value-store.cs

@@ -0,0 +1,144 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+#region Approach 1 (Linear Search of Values)
+public class TimeMap
+{
+    private Dictionary<(string key, string value), int> _timeMap;
+
+    public TimeMap()
+    {
+        _timeMap = new Dictionary<(string key, string value), int>();
+    }
+
+    public void Set(string key, string value, int timestamp)
+    {
+        _timeMap[(key, value)] = timestamp;
+    }
+
+    public string Get(string key, int timestamp)
+    {
+        foreach (var outerKeyValue in _timeMap)
+        {
+            if (key == outerKeyValue.Key.key)
+            {
+                if (timestamp == outerKeyValue.Value)
+                    return outerKeyValue.Key.value;
+                else
+                    return _GetValueOfPreviousLargestTimestamp(key, timestamp);
+            }
+        }
+
+        return "";
+    }
+
+    private string _GetValueOfPreviousLargestTimestamp(string key, int currentTimestamp)
+    {
+        int largestTimeStamp = _GetPreviousLargestTimestampOfKey(key, currentTimestamp);
+
+        return _timeMap
+               .Where(kvp => kvp.Key.key == key && kvp.Value == largestTimeStamp)
+               .Select(kvp => kvp.Key.value)
+               .FirstOrDefault() ?? "";
+    }
+
+    private int _GetPreviousLargestTimestampOfKey(string key, int currentTimestamp)
+    {
+        return _timeMap
+               .Where(kvp => kvp.Key.key == key && currentTimestamp >= kvp.Value)
+               .Select(kvp => kvp.Value) // Select the timestamp values
+               .DefaultIfEmpty(0) // Provide a default value to avoid an empty sequence
+               .Max();
+    }
+}
+#endregion
+
+#region Approach 2 (Binary Search of Values)
+public class TimeMap2
+{
+    private readonly Dictionary<string, List<(int timestamp, string value)>> _dict;
+
+    public TimeMap2()
+    {
+        _dict = new Dictionary<string, List<(int, string)>>();
+    }
+
+    public void Set(string key, string value, int timestamp)
+    {
+        var values = new List<(int, string)>();
+        if (!_dict.ContainsKey(key))
+        {
+            _dict.Add(key, values);
+        }
+        _dict[key].Add((timestamp, value));
+    }
+
+    public string Get(string key, int timestamp)
+    {
+        if (!_dict.ContainsKey(key))
+        {
+            return "";
+        }
+
+        return _GetValueUsingBinarySearch(key, timestamp);
+    }
+
+    private string _GetValueUsingBinarySearch(string key, int timestamp)
+    {
+        var value = _dict[key];
+
+        var left = 0;
+        var right = value.Count;
+        var result = "";
+
+        while (left < right)
+        {
+            var mid = left + (right - left) / 2;
+            if (value[mid].timestamp == timestamp)
+            {
+                return value[mid].value;
+            }
+            else if (value[mid].timestamp < timestamp)
+            {
+                left = mid + 1;
+                result = value[mid].value;
+            }
+            else
+            {
+                right = mid;
+            }
+        }
+
+        return result;
+    }
+}
+#endregion
+
+public class Solution
+{
+    public static void Main(string[] args)
+    {
+        //TimeMap timeMap = new TimeMap();
+        //timeMap.Set("foo", "bar", 1);  // store the key "foo" and value "bar" along with timestamp = 1.
+        //Console.WriteLine(timeMap.Get("foo", 1));         // return "bar"
+        //Console.WriteLine(timeMap.Get("foo", 3));         // return "bar", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
+        //timeMap.Set("foo", "bar2", 4); // store the key "foo" and value "bar2" along with timestamp = 4.
+        //Console.WriteLine(timeMap.Get("foo", 4));         // return "bar2"
+        //Console.WriteLine(timeMap.Get("foo", 5));         // return "bar2"
+
+
+        TimeMap2 timeMap = new TimeMap2();
+        timeMap.Set("love", "high", 10);  // store the key "foo" and value "bar" along with timestamp = 1.
+        timeMap.Set("love", "low", 20);  // store the key "foo" and value "bar" along with timestamp = 1.
+        Console.WriteLine(timeMap.Get("love", 5));         // return ""
+        Console.WriteLine(timeMap.Get("love", 10));         // return "high", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
+        Console.WriteLine(timeMap.Get("love", 15));         // return "high", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
+        Console.WriteLine(timeMap.Get("love", 20));         // return "low", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
+        Console.WriteLine(timeMap.Get("love", 25));         // return "low", since there is no value corresponding to foo at timestamp 3 and timestamp 2, then the only value is at timestamp 1 is "bar".
+
+        Console.ReadKey();
+    }
+
+}
+