SPOJ 4110 Fast Maximum Flow (最大流模板)

题目大意：

无向图，求最大流。

算法讨论：

Dinic可过。终于我的常数还是太大。以后要注意下了。

 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <algorithm>
 #include <iostream>
 #include <queue>
 using namespace std;
 typedef long long ll;

 struct MF{
   static const int N =  + ;
   static const int M =  + ;
   static const ll oo = 10000000000000LL;

   int n, m, s, t, tot, tim;
   int first[N], next[M];
   int u[M], v[M], cur[N], vi[N];
     ll cap[M], flow[M], dis[N];
   int que[N + N];

   void Clear(){
     tot = ;tim = ;
        for(int i = ; i <= n; ++ i) first[i] = -;
   }
   void Add(int from, int to, ll cp, ll flw){
     u[tot] = from; v[tot] = to; cap[tot] = cp; flow[tot] = flw;
     next[tot] = first[u[tot]];
     first[u[tot]] = tot;
     ++ tot;
   }
   bool bfs(){
       ++ tim;
     dis[s] = ;vi[s] = tim;

     int head, tail;
     head = tail = ;
     que[head] = s;
     while(head <= tail){
         for(int i = first[que[head]]; i != -; i = next[i]){
             if(vi[v[i]] != tim && cap[i] > flow[i]){
                 vi[v[i]] = tim;
                 dis[v[i]] = dis[que[head]] + ;
                     que[++ tail] = v[i];
                 }
             }
             ++ head;
         }
        return vi[t] == tim;
   }
   ll dfs(int x, ll a){
     if(x == t || a == ) return a;
     ll flw = , f;
     int &i = cur[x];
     for(i = first[x]; i != -; i = next[i]){
       if(dis[x] +  == dis[v[i]] && (f = dfs(v[i], min(a, cap[i]-flow[i]))) > ){
         flow[i] += f; flow[i^] -= f;
           a -= f; flw += f;
           if(a == ) break;
         }
       }
     return flw;
   }
     ll MaxFlow(int s, int t){
     this->s = s;this->t = t;
     ll flw = ;
     while(bfs()){
       for(int i = ; i <= n; ++ i) cur[i] = ;
       flw += dfs(s, oo);
     }
     return flw;
   }
 }Net;
 int n, m;

 int main(){
     int x, y;
     ll z;
     scanf("%d%d", &n, &m);
     Net.n = n;
     Net.Clear();
     for(int i = ; i <= m; ++ i){
         scanf("%d%d%lld", &x, &y, &z);
         Net.Add(x, y, z, );
         Net.Add(y, x, z, );
     }
     printf("%lld\n", Net.MaxFlow(,Net.n));
     return ;
 }

SPOJ 4110