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Optimize heap operations in min-cost flow slope calculation #30

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Merged
shakayami merged 1 commit into from
Jul 11, 2026
+6 −4
Merged

Optimize heap operations in min-cost flow slope calculation #30

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10 changes: 6 additions & 4 deletions mincostflow.py
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Original file line number Diff line number Diff line change
Expand Up @@ -66,17 +66,19 @@ def slope(self, s, t, flow_limit=-1 - (-1 << 63)):
pe = [0 for i in range(self.n)]
vis = [False for i in range(self.n)]

n = self.n

def dual_ref():
for i in range(self.n):
for i in range(n):
dist[i] = -1 - (-1 << 63)
pv[i] = -1
pe[i] = -1
vis[i] = False
que = []
heapq.heappush(que, (0, s))
heapq.heappush(que, s)
dist[s] = 0
while que:
v = heapq.heappop(que)[1]
v = heapq.heappop(que) % n
if vis[v]:
continue
vis[v] = True
Expand All @@ -100,7 +102,7 @@ def dual_ref():
dist[e["to"]] = dist[v] + cost
pv[e["to"]] = v
pe[e["to"]] = i
heapq.heappush(que, (dist[e["to"]], e["to"]))
heapq.heappush(que, dist[e["to"]] * n + e["to"])
if not (vis[t]):
return False
for v in range(self.n):
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