[Luogu 3973] TJOI2015 線性代數

<題目鏈接>

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
const int MAXP=510,MAXN=250510,MAXM=1501000,INF=0x3f3f3f3f;
int n,m,S,T,cnt,ans,head[MAXN],cur[MAXN],dis[MAXN],c[MAXP],b[MAXP][MAXP];
struct
 
 edge
{
    int nxt,to,w;
}e[MAXM];
void AddEdge(int u,int v,int w)
{
    e[++cnt].nxt=head[u];
    e[cnt].to=v;
    e[cnt].w=w;
    head[u]=cnt;
}
void AddEdges(int u,int v,int w)
{
    AddEdge(u,v,w);
    AddEdge(v,u,0);
}
void Build(void)
{
    m=n*n,T=m+n+1;
    for(int i=1;i<=n;++i)
        for
 
(int j=1,t;j<=n;++j)
        {
            AddEdges(S,t=n*(i-1)+j,b[i][j]);
            AddEdges(t,m+i,INF);
            AddEdges(t,m+j,INF);
        }
    for(int i=1;i<=n;++i)
        AddEdges(m+i,T,c[i]);
}
bool BFS(void)
{
    queue<int> q;
    memset(dis,0,sizeof dis);
    q.push(S);
    dis[S]=1
 
;
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        for(int i=head[u],v;i;i=e[i].nxt)
            if(e[i].w && !dis[v=e[i].to])
            {
                q.push(v);
                dis[v]=dis[u]+1;
            }
    }
    return dis[T];
}
int DFS(int u,int k)
{
    if(u==T || !k)
        return k;
    int sum=0;
    for(int i=cur[u],v,f;i;i=e[i].nxt)
        if(e[i].w && dis[v=e[i].to]==dis[u]+1 && (f=DFS(v,min(k,e[i].w))))
        {
            cur[u]=i;
            e[i].w-=f,e[((i-1)^1)+1].w+=f;
            k-=f,sum+=f;
        }
    if(!sum)
        dis[u]=0;
    return sum;
}
void Dinic(void)
{
    int f;
    while(BFS())
        while(memcpy(cur,head,sizeof head),f=DFS(S,INF))
            ans-=f;
    printf("%d\n",ans);
}
int main(int argc,char *argv[])
{
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n;++j)
        {
            scanf("%d",&b[i][j]);
            ans+=b[i][j];
        }
    for(int i=1;i<=n;++i)
        scanf("%d",&c[i]);
    Build();
    Dinic();
    return 0;
}

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[Luogu 3973] TJOI2015 線性代數