hdu 4240 最大流量路径

题意弄了半天：

给出一个有向图，带边权，src,dst. 求出src到dst的最大流，再求出从src到dst流量最大的路径的流量，求它们的比值。

 #include <cstdio>
 #include <cstring>
 #include <queue>
 #include <vector>
 #define oo 0x3f3f3f3f
 #define maxn 1010
 using namespace std;

 struct Edge {
     int u, v, f, cap;
     Edge( int u, int v, int f, int cap ):u(u),v(v),f(f),cap(cap){}
 };
 struct Dinic {
     int n, src, dst;
     vector<Edge> edge;
     vector<int> g[maxn];
     int dep[maxn], cur[maxn], sig;

     void init( int n, int src, int dst ) {
         this->n = n;
         this->src = src;
         this->dst = dst;
         for( int u=; u<=n; u++ )
             g[u].clear();
         edge.clear();
     }
     void add_edge( int u, int v, int f ) {
         g[u].push_back( edge.size() );
         edge.push_back( Edge(u,v,f,f) );
         g[v].push_back( edge.size() );
         edge.push_back( Edge(v,u,,f) );
     }
     bool bfs() {
         queue<int> qu;
         memset( dep, , sizeof(dep) );
         qu.push( src );
         dep[src] = ;
         while( !qu.empty() ) {
             int u=qu.front();
             qu.pop();
             for( int t=; t<g[u].size(); t++ ) {
                 Edge &e = edge[g[u][t]];
                 if( e.f && !dep[e.v] ) {
                     dep[e.v] = dep[e.u]+;
                     qu.push( e.v );
                 }
             }
         }
         return dep[dst];
     }
     int dfs( int u, int a, int minc ) {
         if( u==dst || a== ) {
             sig = max( minc, sig );
             return a;
         }
         int remain=a, past=, na;
         for( int &t=cur[u]; t<g[u].size(); t++ ) {
             Edge &e = edge[g[u][t]];
             Edge &ve = edge[g[u][t]^];
             if( dep[e.v]==dep[e.u]+ && (na=dfs(e.v,min(remain,e.f),min(minc,e.cap))) ) {
                 remain -= na;
                 past += na;
                 e.f -= na;
                 ve.f += na;
                 if( remain== ) break;
             }
         }
         return past;
     }
     void maxflow( int &tot, int &sig ) {
         tot = sig = ;
         this->sig = ;
         while( bfs() ) {
             memset( cur, , sizeof(cur) );
             tot += dfs(src,oo,oo);
         }
         sig = this->sig;
     }
 };

 int n, m;
 Dinic D;
 int main() {
     int T;
     scanf( "%d", &T );
     while( T-- ) {
         int cas, src, dst;
         scanf( "%d%d%d%d%d", &cas, &n, &m, &src, &dst );
         src++, dst++;
         D.init( n, src, dst );
         for( int i=,u,v,w; i<=m; i++ ) {
             scanf( "%d%d%d", &u, &v, &w );
             u++, v++;
             D.add_edge( u, v, w );
         }
         int tot, sig;
         D.maxflow( tot, sig );
         printf( "%d %.3lf\n", cas, double(tot)/double(sig) );
     }
 }