Update minimum-operations-to-remove-adjacent-ones-in-matrix.py

Author: kamyu104

Python/minimum-operations-to-remove-adjacent-ones-in-matrix.py

@@ -117,6 +117,9 @@ def postprocess(v, u, it):
         for v in unmatched: recurse_iter(v)
 
 
+import collections
+
+
 class Solution(object):
     def minimumOperations(self, grid):
         """