Added a more pythonic implementation of LRU_Cache.[#4628]

Author: yatharthmathur

other/lru_cache_pythonic.py

@@ -0,0 +1,43 @@
+from typing import Any, Hashable
+
+'''
+The following implementation of LRU Cache is one of the most elegant pythonic implementations. 
+It only uses the in-built python dictionary. This works because 
+the Python dictionary maintains the order of insertion of keys and ensures O(1) operations on insert, delete and access.
+'''
+class LRUCache(dict):
+    '''
+    Initialize an LRU Cache with given capacity.
+    capacity : int -> the capacity of the LRU Cache
+    '''
+    def __init__(self, capacity : int):
+        self.remaining:int = capacity
+	
+    '''
+    This method gets the value associated with the key.
+    key : Hashable -> a hashable object that is mapped to a value inside of the LRU cache.
+    returns -> value : Any -> any object that is stored as a value inside of the LRU cache.
+    '''
+    def get(self, key:Hashable)->Any:
+        if key not in self:
+            raise KeyError(f"{key} not found.")
+        val = self.pop(key) # Pop the key-value and re-insert to maintain the order
+        self[key] = val
+        return val
+
+    '''
+    This method puts the value associated with the key provided inside of the LRU cache.
+    key : Hashable -> a hashable object that is mapped to a value inside of the LRU cache.
+    value: Any -> any object that is to be associated with the key inside of the LRU cache.
+    '''
+    def put(self, key:Hashable, value:Any):
+        # To pop the last value inside of the LRU cache
+        if key in self:
+            self.pop(key)
+            self[key] = value
+            return
+
+        if self.remaining > 0: self.remaining -= 1
+        # To pop the least recently used item from the dictionary 
+        else: self.pop(next(iter(self)))
+        self[key] = value