Add Python solution to Q 52

code/52-least-recently-used-cache.py

@@ -0,0 +1,25 @@
+from collections import OrderedDict
+
+
+# O(1) time complexity: __init__, get, and put are O(1)
+# O(n) space complexity: size of the cache
+class LRUCache:
+    def __init__(self, capacity: int):
+        self.cache = OrderedDict()  # cache to store key-value pairs
+        self.capacity = capacity  # max capacity of cache
+
+    def get(self, key: int) -> int:
+        # if key is in the cache, move it to the end
+        if key in self.cache:
+            self.cache.move_to_end(key)
+            return self.cache[key]
+        return -1
+
+    def put(self, key: int, value: int) -> None:
+        # if key is in the cache, move it to the end
+        if key in self.cache:
+            self.cache.move_to_end(key)
+        self.cache[key] = value
+        # if the cache is full, pop the first item (least recently used)
+        if len(self.cache) > self.capacity:
+            self.cache.popitem(last=False)