poj1459

题解：

dinic算法

然后注意一下读入

建立原点汇点

代码：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
const int N=405;
int q[N*N],n,m1,m2,m3,sum,dis[N],x,y,ans,f[N],z,a[N][N];
int bfs()
{
    memset(dis,0xff,sizeof dis);
    dis[1]=0;
    int l=0,r=1;
    q[1]=1;
    while (l<r)
     {
         int j=q[++l];
         for (int i=1;i<=n;i++)
          if (dis[i]<0&&a[j][i]>0)
           {
               dis[i]=dis[j]+1;
               q[++r]=i;
           }
     }
    if (dis[n]>0)return 1;
    return 0; 
}
int find(int x,int low)
{
    int b=0;
    if (x==n)return low;
    for (int i=1;i<=n;i++)
     if (a[x][i]>0&&dis[i]==dis[x]+1&&(b=find(i,min(low,a[x][i]))))
      {
          a[x][i]-=b;
          a[i][x]+=b;
          return b;
      }
    return 0;  
}
int read()
{
    int x=0;char c;
    for (;c<'0'||c>'9';c=getchar());
    for (;c>='0'&&c<='9';c=getchar())x=x*10+c-48;
    return x;
}
int main()
{
    while (~scanf("%d%d%d%d",&n,&m1,&m2,&m3))
     {
         memset(a,0,sizeof a);
        while (m3--)
          {
             x=read();y=read();z=read();
             a[x+2][y+2]+=z;
         }
        while (m1--)
         {
             x=read();y=read();
             a[1][x+2]+=y;
         } 
        while (m2--)
         {
             x=read();y=read();
             a[x+2][n+2]+=y;
         } 
        n+=2; 
        ans=0;int t; 
        while (bfs())
         while (t=find(1,0x7fffffff))
          ans+=t;
        printf("%d
",ans); 
     }
}