Create snapshot-array.py

Author: kamyu104

Python/snapshot-array.py

@@ -0,0 +1,43 @@
+# Time:  set: O(1)
+#        get: O(logn), n is the total number of set
+# Space: O(n)
+
+import collections
+import bisect
+
+
+class SnapshotArray(object):
+
+    def __init__(self, length):
+        """
+        :type length: int
+        """
+        self.__A = collections.defaultdict(lambda: [(-1, 0)])
+        self.__snap_id = 0
+
+
+    def set(self, index, val):
+        """
+        :type index: int
+        :type val: int
+        :rtype: None
+        """
+        self.__A[index].append((self.__snap_id, val))
+
+
+    def snap(self):
+        """
+        :rtype: int
+        """
+        self.__snap_id += 1
+        return self.__snap_id - 1
+
+
+    def get(self, index, snap_id):
+        """
+        :type index: int
+        :type snap_id: int
+        :rtype: int
+        """
+        i = bisect.bisect_right(self.__A[index], (snap_id+1, 0)) - 1
+        return self.__A[index][i][1]