luogu P4015 运输问题

luogu P4015 运输问题

// luogu-judger-enable-o2
#include<queue>
#include<cstdio>
#include<cstring>
#include<algorithm>

#define INF 0x7fffffff
const int maxn = 2007;
using std::min;
using std::queue;
int dis[maxn];bool vis[maxn];
inline int read() {
    int x=0,f=1;
    char c=getchar() ;
    while(c<'0'||c>'9') {if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
    return x*f;
}
int S,T,n,m,pre[maxn],Min_Cost;
struct node{
    int u,v,cost,flow,next;
}edge[(maxn*10)<<1];
int num=1,head[maxn];
void add_edge(int u,int v,int w,int cost)  {
    edge[++num].v=v;edge[num].u=u;edge[num].flow=w;edge[num].cost=cost,edge[num].next=head[u],head[u]=num;
}
bool spfa() {
    memset(vis,0,sizeof vis);
    memset(dis,0x3f,sizeof dis);
    queue<int>que;
    que.push(S);vis[S]=1,dis[S]=0;
    while(!que.empty())  {
        int x=que.front();que.pop(); 
        for(int i=head[x];i;i=edge[i].next ) {
            int v=edge[i].v;
            if(dis[x]+edge[i].cost<dis[v]&&edge[i].flow>0) {
                pre[v]=i;
                dis[v]=dis[x]+edge[i].cost;
                if(!vis[v])vis[v]=1,que.push(v);
            }
        }
        vis[x]=0;
    }
    return dis[T]!=0x3f3f3f3f;
}
void calc() {
    int MF=0x3f3f3f3f;
    for(int i=T;i!=S;i=edge[pre[i]].u) 
        MF=min(MF,edge[pre[i]].flow);
    for(int i=T;i!=S;i=edge[pre[i]].u) {
        edge[pre[i]].flow-=MF;
        edge[pre[i]^1].flow+=MF;
        Min_Cost+=edge[pre[i]].cost*MF;
    }
}
void MFMC() {
    while(spfa())
    calc();
}
int co[107][207];
int ra[107],rb[107];
int main() {
    m=read();n=read();S=0,T=m+n+1;
    for(int i=1;i<=m;++i) 
        add_edge(S,i,ra[i]=read(),0),add_edge(i,S,0,0);
    for(int i=1;i<=n;++i)
        add_edge(m+i,T,rb[i]=read(),0),add_edge(T,m+i,0,0);
    for(int i=1;i<=m;++i) 
        for(int j=m+1;j<=m+n;++j)
            add_edge(i,j,INF,co[i][j]=read()),add_edge(j,i,0,-co[i][j]);
    MFMC();printf("%d
",Min_Cost);
    Min_Cost=0,num=1,memset(head,0,sizeof head);
    
    for(int i=1;i<=m;++i) 
        add_edge(S,i,ra[i],0),add_edge(i,S,0,0);
    for(int i=1;i<=n;++i)
        add_edge(m+i,T,rb[i],0),add_edge(T,m+i,0,0);
    for(int i=1;i<=m;++i) 
        for(int j=m+1;j<=m+n;++j)
            add_edge(i,j,INF,-co[i][j]),add_edge(j,i,0,co[i][j]);
    MFMC();
    printf("%d
",-Min_Cost);
    return 0;
}
原文地址:https://www.cnblogs.com/sssy/p/8562941.html