[rllib] arr[end] was excluded when end is not None (#1931)

Looks good, thanks!

Author: royf

python/ray/rllib/optimizers/segment_tree.py

@@ -78,10 +78,9 @@ def reduce(self, start=0, end=None):
           elements.
         """
         if end is None:
-            end = self._capacity
+            end = self._capacity - 1
         if end < 0:
             end += self._capacity
-        end -= 1
         return self._reduce_helper(start, end, 1, 0, self._capacity - 1)
 
     def __setitem__(self, idx, val):