Add TimeMap implementation with binary search and tests

Implemented a `TimeMap` class featuring `set` and `get` methods to handle time-based key-value storage using binary search for efficient retrieval. Added comprehensive unit tests to validate functionality across multiple scenarios, including edge cases and multiple keys.

Author: nicholasadamou

Binary Search/time_based_key_value_store.py

@@ -0,0 +1,76 @@
+# https://neetcode.io/problems/time-based-key-value-store
+
+import unittest
+
+
+class TimeMap:
+    def __init__(self):
+        self.history = {}
+
+    def set(self, key: str, value: str, timestamp: int) -> None:
+        if key not in self.history:
+            self.history[key] = []
+
+        self.history[key].append([value, timestamp])
+
+    def get(self, key: str, timestamp: int) -> str:
+        result = ""  # Most recent value for given timestamp
+        values = self.history.get(key, [])
+
+        left = 0
+        right = len(values) - 1
+
+        while left <= right:
+            mid = (left + right) // 2
+
+            prev_timestamp = values[mid][1]
+
+            if prev_timestamp <= timestamp:
+                result = values[mid][0]
+
+                left = mid + 1
+            else:
+                right = mid - 1
+
+        return result
+
+
+class TestTimeMap(unittest.TestCase):
+    def setUp(self):
+        self.time_map = TimeMap()
+
+    def test_set_and_get_single_value(self):
+        self.time_map.set("foo", "bar", 1)
+        self.assertEqual(self.time_map.get("foo", 1), "bar")
+
+    def test_get_most_recent_value(self):
+        self.time_map.set("foo", "bar", 1)
+        self.time_map.set("foo", "bar2", 2)
+        self.assertEqual(self.time_map.get("foo", 2), "bar2")
+        self.assertEqual(self.time_map.get("foo", 3), "bar2")
+
+    def test_get_before_any_set_value(self):
+        self.assertEqual(self.time_map.get("foo", 1), "")
+
+    def test_key_with_multiple_values_and_timestamp(self):
+        self.time_map.set("key1", "alpha", 1)
+        self.time_map.set("key1", "beta", 3)
+        self.time_map.set("key1", "gamma", 5)
+
+        # Exact match for timestamps
+        self.assertEqual(self.time_map.get("key1", 3), "beta")
+        self.assertEqual(self.time_map.get("key1", 5), "gamma")
+
+        # Fetching closest lower timestamp
+        self.assertEqual(self.time_map.get("key1", 4), "beta")
+        self.assertEqual(self.time_map.get("key1", 2), "alpha")
+
+        # Fetching before the first timestamp
+        self.assertEqual(self.time_map.get("key1", 0), "")
+
+    def test_multiple_keys(self):
+        self.time_map.set("foo", "bar", 1)
+        self.time_map.set("baz", "qux", 2)
+        self.assertEqual(self.time_map.get("foo", 1), "bar")
+        self.assertEqual(self.time_map.get("baz", 2), "qux")
+        self.assertEqual(self.time_map.get("baz", 1), "")