网络流模板

EK算法

#include<bits/stdc++.h>
using namespace std;

#define debug puts("YES");
#define rep(x,y,z) for(int (x)=(y);(x)<(z);(x)++)
#define ll long long

#define lrt int l,int r,int rt
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define root l,r,rt
#define mst(a,b) memset((a),(b),sizeof(a))
#define pii pair<int,int>
#define fi first
#define se second
#define mk(x,y) make_pair(x,y)
const int mod=1e9+7;
const int maxn=120;
const int ub=1e6;
const double inf=1e-4;
ll powmod(ll x,ll y){ll t; for(t=1;y;y>>=1,x=x*x%mod) if(y&1) t=t*x%mod; return t;}
ll gcd(ll x,ll y){return y?gcd(y,x%y):x;}

int n,np,nc,m,cap[maxn][maxn];
int from,to,value;

int EK(int s,int t){
    queue<int> Q;
    int flow[maxn][maxn],ret=0;
    int minv[maxn],pre[maxn];///最小流量,前继链接
    mst(flow,0);///局部变量要初始化
    while(1){
        Q.push(n);
        mst(minv,0),minv[n]=mod;
        while(!Q.empty()){
            int tp=Q.front();Q.pop();
            for(int i=0;i<=n+1;i++) if(cap[tp][i]>flow[tp][i]&&!minv[i]){
                pre[i]=tp;
                Q.push(i);
                minv[i]=min(minv[tp],cap[tp][i]-flow[tp][i]);
            }
        }
        if(minv[t]==0) break;///无法再约束
        for(int i=t;i!=s;i=pre[i]){
            flow[i][pre[i]]-=minv[t];
            flow[pre[i]][i]+=minv[t];
        }
        ret+=minv[t];
    }
    return ret;
}

int main(){
    while(scanf("%d %d %d %d",&n,&np,&nc,&m)!=EOF){
        mst(cap,0);
        while(m--){
            scanf(" (%d,%d)%d",&from,&to,&value);
            cap[from][to]=value;
        }
        while(np--){
            scanf(" (%d)%d",&from,&value);
            cap[n][from]=value;
        }
        while(nc--){
            scanf(" (%d)%d",&to,&value);
            cap[to][n+1]=value;
        }
        ///初始网络构建完毕
        printf("%d\n",EK(n,n+1));
    }
    return 0;
}

DINIC算法

#include<iostream>
#include<cstring>
#include<queue>
#include<cstdio>
//#include<bits/stdc++.h>
using namespace std;

#define debug puts("YES");
#define rep(x,y,z) for(int (x)=(y);(x)<(z);(x)++)
#define ll long long

#define lrt int l,int r,int rt
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define root l,r,rt
#define mst(a,b) memset((a),(b),sizeof(a))
#define pii pair<int,int>
#define fi first
#define se second
#define mk(x,y) make_pair(x,y)
const int mod=1e9+7;
#define INF 0x3f3f3f3f
const int maxn=1e5+5;
const int maxm=5e2+5;
const int ub=1e6;
ll powmod(ll x,ll y){ll t; for(t=1;y;y>>=1,x=x*x%mod) if(y&1) t=t*x%mod; return t;}
ll gcd(ll x,ll y){return y?gcd(y,x%y):x;}
int m,n,k,S,T;
struct node{
    int u,nxt,flow;
}e[maxn];
int head[maxm],tot=0;
void init(){
    mst(head,-1),tot=0;
}
void add(int x,int y,int v){
    e[tot].u=y,e[tot].nxt=head[x],e[tot].flow=v;
    head[x]=tot++;
    e[tot].u=x,e[tot].nxt=head[y],e[tot].flow=0;
    head[y]=tot++;
}
int d[maxm];
bool bfs(){
    mst(d,-1),d[S]=0;
    queue<int> p;p.push(S);
    while(!p.empty()){
        int x=p.front();p.pop();
        for(int i=head[x];~i;i=e[i].nxt){
            int y=e[i].u;
            if(e[i].flow&&d[y]==-1){
                d[y]=d[x]+1;
                p.push(y);
                if(y==T) return true;
            }
        }
    }
    return false;
}
int dfs(int x,int all){
    if(x==T) return all;
    int cost=0;
    for(int i=head[x];~i;i=e[i].nxt){
        int y=e[i].u;
        if(e[i].flow&&d[y]==d[x]+1){
            int tmp=dfs(y,min(e[i].flow,all-cost));
            e[i].flow-=tmp;
            e[i^1].flow+=tmp;
            cost+=tmp;
         if(cost==all) break;
        }
    }
    ///if(cost==0) d[x]=-1;
    return cost;
}
int dinic(){
    int ret=0;
    while(bfs()) ret+=dfs(S,INF);
    return ret;
}
int pre[maxm],a[maxm];///上一个出现的
int main(){
        while(~scanf("%d%d",&m,&n)){
        S=n+1,T=S+1;
        init();mst(pre,0);
        rep(i,1,m+1) scanf("%d",&a[i]);
        rep(i,1,n+1){
            int k,x;scanf("%d",&k);
            rep(j,0,k){
                scanf("%d",&x);
                if(pre[x]==0) add(S,i,a[x]);
                else add(pre[x],i,INF);
                pre[x]=i;
            }
            scanf("%d",&x);
            add(i,T,x);
        }
        printf("%d\n",dinic());
    }
    return 0;
}