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Add graph/bounded_flow.cc 

Signed-off-by: subcrip <contact@subc.rip>
This commit is contained in:
subcrip 2024-05-20 13:31:30 +08:00
parent eb518dfef6
commit 4e03e50bcc
1 changed files with 39 additions and 0 deletions
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graph/bounded_flow.cc Normal file
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struct bounded_flow {
int n, m, S, T;
dinic net;
ll sum;
vector<ll> fl;
vector<ll> init;
bounded_flow(int n, int m) : sum(0), n(n), m(m), S(0), T(n + 1), net(n + 1), fl(m), init(n + 1) {}
void add_edge(int from, int to, ll low, ll high, int edge_id = -1) {
if (edge_id != -1) {
fl[edge_id] += low;
}
net.add_edge(from, to, high - low, edge_id, -1);
init[to] += low, init[from] -= low;
}
optional<pair<ll, vector<ll>>> run(int s, int t) {
for (int i = 1; i <= n; ++i) {
if (init[i] > 0) {
net.add_edge(S, i, init[i], -1, -1);
sum += init[i];
} else if (init[i] < 0) {
net.add_edge(i, T, -init[i], -1, -1);
}
}
net.add_edge(t, s, INFLL, -1, -1);
if (sum != net.run(S, T)) {
return nullopt;
} else {
auto res_flow = net.run(s, t);
for (int from = 1; from <= n; ++from) {
for (auto&& [to, cap, flow, rev, mark] : net.edges[from]) {
if (mark != -1) {
fl[mark] = flow;
}
}
}
return {{res_flow, fl}};
}
}
};