洛谷4014最大/小费用最大流

题目：https://www.luogu.org/problemnew/show/P4014

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
typedef long long ll;
const int N=205,cN=20405;
const ll INF=0x7fffffff;
int n,head[N],incf[N],pre[N],xnt=1,t;
ll dis[N],ans;
bool in[N];
struct Edge{
    int next,from,to,cap;
    ll w;
    Edge(int n=0,int f=0,int t=0,int c=0,ll w=0):next(n),from(f),to(t),cap(c),w(w) {}
}edge[cN],tmp[cN];
bool spfa()
{
    queue<int> q;
    memset(dis,-2,sizeof dis);
    q.push(0);in[0]=1;
    dis[0]=0;incf[0]=INF;pre[t]=0;
    while(q.size())
    {
        int k=q.front();q.pop();in[k]=0;
        for(int i=head[k],v;i;i=edge[i].next)
            if(edge[i].cap&&dis[k]+edge[i].w>dis[v=edge[i].to])
            {
                dis[v]=dis[k]+edge[i].w;
                incf[v]=min(edge[i].cap,incf[k]);
                pre[v]=i;
//                printf("v=%d pre[v]=%d
",v,pre[v]);
                if(!in[v])q.push(v),in[v]=1;
            }
    }
    return pre[t];
}
bool spfa1()
{
    queue<int> q;
    memset(dis,1,sizeof dis);
    q.push(0);in[0]=1;
    dis[0]=0;incf[0]=INF;pre[t]=0;
    while(q.size())
    {
        int k=q.front();q.pop();in[k]=0;
        for(int i=head[k],v;i;i=tmp[i].next)
            if(tmp[i].cap&&dis[k]+tmp[i].w<dis[v=tmp[i].to])
            {
                dis[v]=dis[k]+tmp[i].w;
                incf[v]=min(tmp[i].cap,incf[k]);
                pre[v]=i;
//                printf("v=%d pre[v]=%d
",v,pre[v]);
                if(!in[v])q.push(v),in[v]=1;
            }
    }
    return pre[t];
}
void ek()
{
    for(int k=pre[t];k;k=pre[edge[k].from])
    {
//        printf("(%d)",edge[k].to);
        edge[k].cap-=incf[t];
        edge[k^1].cap+=incf[t];
        ans+=edge[k].w*incf[t];
    }
}
void ek1()
{
    for(int k=pre[t];k;k=pre[tmp[k].from])
    {
//        printf("(%d)",edge[k].to);
        tmp[k].cap-=incf[t];
        tmp[k^1].cap+=incf[t];
        ans+=tmp[k].w*incf[t];
    }
}
int main()
{
    scanf("%d",&n);
    ll x;t=2*n+1;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
        {
            scanf("%lld",&x);
            edge[++xnt]=Edge(head[i],i,j+n,1,x);head[i]=xnt;
            edge[++xnt]=Edge(head[j+n],j+n,i,0,-x);head[j+n]=xnt;
        }
    for(int i=1;i<=n;i++)
    {
        edge[++xnt]=Edge(head[0],0,i,1,0);head[0]=xnt;
        edge[++xnt]=Edge(head[i],i,0,0,0);head[i]=xnt;
        edge[++xnt]=Edge(head[i+n],i+n,t,1,0);head[i+n]=xnt;
        edge[++xnt]=Edge(head[t],t,i+n,0,0);head[t]=xnt;
    }
    memcpy(tmp,edge,sizeof edge);
    while(spfa1())
        ek1();
    printf("%lld
",ans);
    ans=0;
    while(spfa())
        ek();
    printf("%lld",ans);
    return 0;
}