zoj2314

题解：

有上限的网络流

基本模板

代码：

#include<bits/stdc++.h>
using namespace std;
const int N=;
int ne[N],num,n,m,d[N],S,T,a,b,c,low[N],fi[N],zz[N],sl[N],dis[N],q[N];
void jb(int x,int y,int z)
{
    ne[num]=fi[x];
    fi[x]=num;
    zz[num]=y;
    sl[num++]=z;
    swap(x,y);
    z=;
    ne[num]=fi[x];
    fi[x]=num;
    zz[num]=y;
    sl[num++]=z;
}
int bfs()
{
    memset(dis,0xff,sizeof dis);
    dis[]=;
    int l=,r=;
    q[]=;
    while (l<r)
     {
         int j=q[++l];
         for (int i=fi[j];i!=-;i=ne[i])
          if (dis[zz[i]]<&&sl[i]>)
           {
               dis[zz[i]]=dis[j]+;
               q[++r]=zz[i];
           }
     }
    if (dis[n]>)return ;
    return ;
}
int find(int x,int low)
{
    int b=;
    if (x==n)return low;
    for (int i=fi[x];i!=-;i=ne[i])
     if (sl[i]>&&dis[zz[i]]==dis[x]+&&(b=find(zz[i],min(low,sl[i]))))
      {
          sl[i]-=b;
          sl[i^]+=b;
          return b;
      }
    return ;
}
int main()
{
    scanf("%d",&T);
    while (T--)
     {
         memset(fi,-,sizeof fi);
         num=;
         memset(d,,sizeof d);
         scanf("%d%d",&n,&m);
         for (int i=;i<m;i++)
          {
              scanf("%d%d%d%d",&a,&b,&low[i],&c);
              jb(a+,b+,c-low[i]);
              d[a]+=low[i];d[b]-=low[i];
          }
         int tot=;
        for (int i=;i<=n;i++)
         {
             if (d[i]<)jb(,i+,-d[i]);
             else jb(i+,n+,d[i]),tot+=d[i];
         }
        n+=;
        int t,ans=;
        while (bfs())
         while (t=find(,1e9))ans+=t;
        if (tot!=ans)puts("NO");
        else
         {
             puts("YES");
             for (int i=;i<m;i++)
              printf("%d\n",sl[(i<<)^]+low[i]);
         }
        puts("");
     }
}