update 146

Author: KaidiGuo

Hashing/146. LRU Cache.py

@@ -0,0 +1,34 @@
+# Learning how to use OrderedDict() and its popitem(last=False) function to pop the first in element
+
+
+class LRUCache:
+
+    def __init__(self, capacity: int):
+        self.capacity = capacity
+        self.dict = collections.OrderedDict()
+        
+
+    def get(self, key: int) -> int:
+        if key in self.dict:
+            v = self.dict[key]
+            del self.dict[key]
+            self.dict[key] = v
+            return self.dict[key]
+        else:
+            return -1
+
+    def put(self, key: int, value: int) -> None:
+        if key in self.dict:
+            del self.dict[key]
+            self.dict[key] = value
+            
+        else:
+            if len(self.dict) >= self.capacity:
+                self.dict.popitem(last=False)
+            self.dict[key] = value
+            
+
+# Your LRUCache object will be instantiated and called as such:
+# obj = LRUCache(capacity)
+# param_1 = obj.get(key)
+# obj.put(key,value)