Implement scan queue as a list instead of deque

python/mwmatching.py

@@ -6,7 +6,6 @@ from __future__ import annotations
 
 import sys
 import math
-import collections
 from collections.abc import Sequence
 from typing import NamedTuple, Optional
 
@@ -600,7 +599,7 @@ class _MatchingContext:
         self.vertex_best_edge: list[int] = num_vertex * [-1]
 
         # Queue of S-vertices to be scanned.
-        self.scan_queue: collections.deque[int] = collections.deque()
+        self.scan_queue: list[int] = []
 
     def __del__(self) -> None:
         """Delete reference cycles during cleanup of the matching context."""
@@ -1412,10 +1411,7 @@ class _MatchingContext:
 
         # Process S-vertices waiting to be scanned.
         # This loop runs through O(n) iterations per stage.
-        while self.scan_queue:
-
-            # Take a vertex from the queue.
-            x = self.scan_queue.popleft()
+        for x in self.scan_queue:
 
             # Double-check that "x" is an S-vertex.
             bx = self.vertex_set_node[x].find()
@@ -1464,6 +1460,8 @@ class _MatchingContext:
                     # tracked.
                     self.lset_add_vertex_edge(y, by, e)
 
+        self.scan_queue.clear()
+
     #
     # Delta steps:
     #