网络最大流最短增广路Dinic算法模板

#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<vector>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn = 30000 + 10;
const int INF = 0x7FFFFFFF;
struct Edge
{
int from, to, cap, flow;
Edge(int u, int v, int c, int f) :from(u), to(v), cap(c), flow(f){}
};
vector<Edge>edges;
vector<int>G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
int n, m, s, t;

void init()
{
for (int i = 0; i < maxn; i++)
G[i].clear();
edges.clear();
}
void AddEdge(int from, int to, int cap)
{
edges.push_back(Edge(from, to, cap, 0));
edges.push_back(Edge(to, from, 0, 0));
int w = edges.size();
G[from].push_back(w - 2);
G[to].push_back(w - 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)
{
edges[G[x][i]].flow+=f;
edges[G[x][i] ^ 1].flow-=f;
flow+=f;
a-=f;
if(a==0) break;
}
}
if(!flow) d[x] = -1;
return flow;
}
int dinic(int s, int t)
{
int flow = 0;
while (BFS())
{
memset(cur, 0, sizeof(cur));
flow += DFS(s, INF);
}
return flow;
}

//输入输出
int main()
{
int T,ii;
scanf("%d",&T);
for(ii=1;ii<=T;ii++)
{

/*初始化*/
edges.clear();
for(int i=0;i<maxn;i++) G[i].clear();
/*如果想要多次求网络流，求完一次后，先把每条弧的流量清空*/

int mm;
scanf("%d%d",&n,&mm);
s=1;t=n;//设置源点和汇点
while(mm--)
{
int uu,vv,cc;
scanf("%d%d%d",&uu,&vv,&cc);
AddEdge(uu,vv,cc);
}
printf("Case %d: %d\n",ii,dinic(s,t));
}
return 0;
}