poj 3308 (最大流)

#include<stdio.h>#include<math.h>#include<string.h>const int N=3000;#define inf 100.0int head[N],num,ans,start,end,gap[N],dis[N];struct edge{int st,ed,next;double flow;}e[N*100];void addedge(int x,int y,double w){e[num].st=x;e[num].ed=y;e[num].flow=w;e[num].next=head[x];head[x]=num++;e[num].st=y;e[num].ed=x;e[num].flow=0;e[num].next=head[y];head[y]=num++;}double dfs(int u,double minflow){if(u==end)return minflow;int i,v;double f,flow=0.0;for(i=head[u];i!=-1;i=e[i].next){v=e[i].ed;if(e[i].flow>0){if(dis[v]+1==dis[u]){f=dfs(v,e[i].flow>minflow-flow?minflow-flow:e[i].flow);flow+=f;e[i].flow-=f;e[i^1].flow+=f;if(minflow-flow<=1e-8)return flow;  if(dis[start]>=ans)return flow;  }}}if(--gap[dis[u]]==0)dis[start]=ans;dis[u]++;gap[dis[u]]++;return flow;}double isap(){double maxflow=0.0;memset(gap,0,sizeof(gap));memset(dis,0,sizeof(dis));gap[0]=ans;while(dis[start]<ans)maxflow+=dfs(start,inf);return maxflow;}int main(){int i,n,m,k,x,y,t;double w;scanf("%d",&t);while(t--){scanf("%d%d%d",&n,&m,&k);memset(head,-1,sizeof(head));num=0;start=0;end=n+m+1;ans=end+1;for(i=1;i<=n;i++){scanf("%lf",&w);addedge(start,i,log(w));}for(i=1;i<=m;i++){scanf("%lf",&w);addedge(i+n,end,log(w));}while(k--){scanf("%d%d",&x,&y);addedge(x,y+n,inf);}w=isap();printf("%.4lf\n",exp(w));}return 0;}