网络流模板 Dinic+ISAP

本文主要是介绍网络流模板 Dinic+ISAP，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

dinic递归版，堆栈溢出可以手动扩栈，改成非递归版本，或者改用效率更高的ISAP。

struct Edge
{
int from, to, cap, flow;
Edge(){}
Edge(int from, int to, int cap, int flow) : from(from), to(to), cap(cap), flow(flow){}
};
int n, m, s, t;
vector <Edge> edges;
vector <int> G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
void AddEdge(int from, int to, int cap)
{
edges.push_back(Edge(from, to, cap, 0));
edges.push_back(Edge(to, from, 0, 0));
m = edges.size();
G[from].push_back(m-2);
G[to].push_back(m-1); 
}
bool BFS()
{
memset(vis, 0, sizeof(vis));
queue <int> Q;
Q.push(s);
d[s] = 0;
vis[s] = 1;
while(!Q.empty())
{
int x = Q.front(); Q.pop();
for(int i = 0; i < G[x].size(); i++)
{
Edge& e = edges[G[x][i]];
if(!vis[e.to] && e.cap > e.flow)
{
vis[e.to] = 1;
d[e.to] = d[x] + 1;
Q.push(e.to);
}
}
}
return vis[t];
}
int DFS(int x, int a)
{
if(x == t || a == 0)
return a;
int flow = 0, f;
for(int& i = cur[x]; i < G[x].size(); i++)
{
Edge& e = edges[G[x][i]];
if(d[x] + 1 == d[e.to] && (f = DFS(e.to, min(a, e.cap-e.flow))) > 0)
{
e.flow += f;
edges[G[x][i]^1].flow -= f;
flow += f;
a -= f;
if(a == 0)
break;
}
}
return flow;
}
int Maxflow()
{
int flow = 0;
while(BFS())
{
memset(cur, 0, sizeof(cur));
flow += DFS(s, INF);
}
return flow;
}

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