src/jiangly/graph/06C-Max-Flow.hpp
Code
/** 最大流（MaxFlow 新版）
* 2023-07-21: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=62915815
**/
constexpr int inf = 1E9;
template<class T>
struct MaxFlow {
struct _Edge {
int to;
T cap;
_Edge(int to, T cap) : to(to), cap(cap) {}
};
int n;
std::vector<_Edge> e;
std::vector<std::vector<int>> g;
std::vector<int> cur, h;
MaxFlow() {}
MaxFlow(int n) {
init(n);
}
void init(int n) {
this->n = n;
e.clear();
g.assign(n, {});
cur.resize(n);
h.resize(n);
}
bool bfs(int s, int t) {
h.assign(n, -1);
std::queue<int> que;
h[s] = 0;
que.push(s);
while (!que.empty()) {
const int u = que.front();
que.pop();
for (int i : g[u]) {
auto [v, c] = e[i];
if (c > 0 && h[v] == -1) {
h[v] = h[u] + 1;
if (v == t) {
return true;
}
que.push(v);
}
}
}
return false;
}
T dfs(int u, int t, T f) {
if (u == t) {
return f;
}
auto r = f;
for (int &i = cur[u]; i < int(g[u].size()); ++i) {
const int j = g[u][i];
auto [v, c] = e[j];
if (c > 0 && h[v] == h[u] + 1) {
auto a = dfs(v, t, std::min(r, c));
e[j].cap -= a;
e[j ^ 1].cap += a;
r -= a;
if (r == 0) {
return f;
}
}
}
return f - r;
}
void addEdge(int u, int v, T c) {
g[u].push_back(e.size());
e.emplace_back(v, c);
g[v].push_back(e.size());
e.emplace_back(u, 0);
}
T flow(int s, int t) {
T ans = 0;
while (bfs(s, t)) {
cur.assign(n, 0);
ans += dfs(s, t, std::numeric_limits<T>::max());
}
return ans;
}
std::vector<bool> minCut() {
std::vector<bool> c(n);
for (int i = 0; i < n; i++) {
c[i] = (h[i] != -1);
}
return c;
}
struct Edge {
int from;
int to;
T cap;
T flow;
};
std::vector<Edge> edges() {
std::vector<Edge> a;
for (int i = 0; i < e.size(); i += 2) {
Edge x;
x.from = e[i + 1].to;
x.to = e[i].to;
x.cap = e[i].cap + e[i + 1].cap;
x.flow = e[i + 1].cap;
a.push_back(x);
}
return a;
}
};
#line 1 "src/jiangly/graph/06C-Max-Flow.hpp"
/** 最大流（MaxFlow 新版）
* 2023-07-21: https://ac.nowcoder.com/acm/contest/view-submission?submissionId=62915815
**/
constexpr int inf = 1E9;
template<class T>
struct MaxFlow {
struct _Edge {
int to;
T cap;
_Edge(int to, T cap) : to(to), cap(cap) {}
};
int n;
std::vector<_Edge> e;
std::vector<std::vector<int>> g;
std::vector<int> cur, h;
MaxFlow() {}
MaxFlow(int n) {
init(n);
}
void init(int n) {
this->n = n;
e.clear();
g.assign(n, {});
cur.resize(n);
h.resize(n);
}
bool bfs(int s, int t) {
h.assign(n, -1);
std::queue<int> que;
h[s] = 0;
que.push(s);
while (!que.empty()) {
const int u = que.front();
que.pop();
for (int i : g[u]) {
auto [v, c] = e[i];
if (c > 0 && h[v] == -1) {
h[v] = h[u] + 1;
if (v == t) {
return true;
}
que.push(v);
}
}
}
return false;
}
T dfs(int u, int t, T f) {
if (u == t) {
return f;
}
auto r = f;
for (int &i = cur[u]; i < int(g[u].size()); ++i) {
const int j = g[u][i];
auto [v, c] = e[j];
if (c > 0 && h[v] == h[u] + 1) {
auto a = dfs(v, t, std::min(r, c));
e[j].cap -= a;
e[j ^ 1].cap += a;
r -= a;
if (r == 0) {
return f;
}
}
}
return f - r;
}
void addEdge(int u, int v, T c) {
g[u].push_back(e.size());
e.emplace_back(v, c);
g[v].push_back(e.size());
e.emplace_back(u, 0);
}
T flow(int s, int t) {
T ans = 0;
while (bfs(s, t)) {
cur.assign(n, 0);
ans += dfs(s, t, std::numeric_limits<T>::max());
}
return ans;
}
std::vector<bool> minCut() {
std::vector<bool> c(n);
for (int i = 0; i < n; i++) {
c[i] = (h[i] != -1);
}
return c;
}
struct Edge {
int from;
int to;
T cap;
T flow;
};
std::vector<Edge> edges() {
std::vector<Edge> a;
for (int i = 0; i < e.size(); i += 2) {
Edge x;
x.from = e[i + 1].to;
x.to = e[i].to;
x.cap = e[i].cap + e[i + 1].cap;
x.flow = e[i + 1].cap;
a.push_back(x);
}
return a;
}
};
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