【上下界网络流】ZOJ2314 Reactor Cooling

题面在这里

上下界网络流的裸题……

直接套用“无源汇有上下界可行流”即可

示例程序：

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn=305,maxe=100005,INF=0x3f3f3f3f;int tst,n,e,SS,TT,a[maxn],l[maxe],r[maxe];int tot,lnk[maxn],nxt[maxe],son[maxe],flw[maxe],cap[maxe];inline int red(){    int tot=0,f=1;char ch=getchar();    while (ch<'0'||'9'<ch) {if (ch=='-') f=-f;ch=getchar();}    while ('0'<=ch&&ch<='9') tot=tot*10+ch-48,ch=getchar();    return tot*f;}inline void add(int x,int y,int z){// printf("%d %d %d\n",x,y,z);    son[++tot]=y;nxt[tot]=lnk[x];lnk[x]=tot;flw[tot]=0;cap[tot]=z;    son[++tot]=x;nxt[tot]=lnk[y];lnk[y]=tot;flw[tot]=0;cap[tot]=0;}int d[maxn],que[maxn],pos[maxn];bool bfs(int S,int T){    memset(d,63,sizeof(d));    int hed=0,til=1;    que[1]=S;d[S]=0;    while (hed!=til)     for (int j=lnk[que[++hed]];j;j=nxt[j])      if (d[son[j]]==INF&&flw[j]<cap[j])       que[++til]=son[j],d[son[j]]=d[que[hed]]+1;    return d[T]!=INF;}int dfs(int x,int flow,int T){    if (x==T||flow==0) return flow;    int f,res=0;    for (int &j=pos[x];j;j=nxt[j])     if (d[x]+1==d[son[j]]&&(f=dfs(son[j],min(flow,cap[j]-flw[j]),T))>0){        flw[j]+=f;flw[j^1]-=f;        res+=f;flow-=f;        if (flow==0) break;     }    return res;}void Dinic(){    while (bfs(SS,TT)){        memcpy(pos,lnk,sizeof(pos));        dfs(SS,INF,TT);    }}int main(){    tst=red();    while (tst--){        n=red(),e=red();tot=1;SS=n+1;TT=n+2;        memset(lnk,0,sizeof(lnk));        memset(a,0,sizeof(a));        for (int i=1,x,y;i<=e;i++)         x=red(),y=red(),l[i]=red(),r[i]=red(),add(x,y,r[i]-l[i]),a[x]-=l[i],a[y]+=l[i];        for (int i=1;i<=n;i++)         if (a[i]>0) add(SS,i,a[i]);else add(i,TT,-a[i]);        Dinic();        bool suc=1;        for (int i=1;i<=n;i++)         if(flw[(e+i)*2]<cap[(e+i)*2]) {suc=0;break;}        if (suc){            printf("YES\n");            for (int i=1;i<=e;i++)             printf("%d\n",l[i]+flw[i*2]);            putchar('\n');        }else printf("NO\n\n");    }    return 0;}