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nit picking optimization of mincostflow #67

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Merged
yosupo06 merged 1 commit into from
Nov 14, 2020
Merged

nit picking optimization of mincostflow #67

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27 changes: 15 additions & 12 deletions atcoder/mincostflow.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -72,23 +72,25 @@ template <class Cap, class Cost> struct mcf_graph {
std::vector<Cost> dual(_n, 0), dist(_n);
std::vector<int> pv(_n), pe(_n);
std::vector<bool> vis(_n);
struct Q {
Cost key;
int to;
bool operator<(Q r) const { return key > r.key; }
};
std::vector<Q> que;
auto dual_ref = [&]() {
std::fill(dist.begin(), dist.end(),
std::numeric_limits<Cost>::max());
std::fill(pv.begin(), pv.end(), -1);
std::fill(pe.begin(), pe.end(), -1);
std::fill(vis.begin(), vis.end(), false);
struct Q {
Cost key;
int to;
bool operator<(Q r) const { return key > r.key; }
};
std::priority_queue<Q> que;
que.clear();

dist[s] = 0;
que.push(Q{0, s});
que.push_back(Q{0, s});
std::push_heap(que.begin(), que.end());
while (!que.empty()) {
int v = que.top().to;
que.pop();
int v = que.front().to;
std::pop_heap(que.begin(), que.end());
que.pop_back();
if (vis[v]) continue;
vis[v] = true;
if (v == t) break;
Expand All @@ -105,7 +107,8 @@ template <class Cap, class Cost> struct mcf_graph {
dist[e.to] = dist[v] + cost;
pv[e.to] = v;
pe[e.to] = i;
que.push(Q{dist[e.to], e.to});
que.push_back(Q{dist[e.to], e.to});
std::push_heap(que.begin(), que.end());
}
}
}
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