Create number-of-recent-calls.py

Author: kamyu104

Diff for: Python/number-of-recent-calls.py

@@ -0,0 +1,20 @@
+# Time:  O(1) on average
+# Space: O(w), w means the size of the last milliseconds.
+
+import collections
+
+
+class RecentCounter(object):
+
+    def __init__(self):
+        self.__q = collections.deque()
+
+    def ping(self, t):
+        """
+        :type t: int
+        :rtype: int
+        """
+        self.__q.append(t)
+        while self.__q[0] < t-3000:
+            self.__q.popleft()
+        return len(self.__q)