POJ 1459 最大流 第二题

http://poj.org/problem?id=1459

也是网络流的基础，只是虚拟出一个源点和终点，对应的生产值和消费值就加到与源点和终点的边上，然后做一次bfs就好了。

 #include <iostream>
 #include <cstdio>
 #include <queue>
 #include <algorithm>
 #define INF 999999999
 //#define OPEN_FILE
 using namespace std;

 const int MAXN = ;
 int cap[MAXN][MAXN], flow[MAXN][MAXN], p[MAXN], c[MAXN], f[MAXN];
 int n, ans;

 void get_cap(char s[])
 {
     int i, u, v, w;
     u = ;
     for (i = ; s[i] != ','; i++){
         u = u *  + (s[i] - '');
     }
     v = ;
     for (++i; s[i] != ')'; i++){
         v = v *  + (s[i] - '');
     }
     int len = strlen(s);
     w = ;
     for (++i; i < len; i++){
         w = w *  + (s[i] - '');
     }
     cap[u][v] = w;
 }

 void get_pc(char s[], int* t, int o)
 {
     int i, u, w;
     u = ;
     for (i = ; s[i] != ')'; i++){
         u = u *  + (s[i] - '');
     }
     int len = strlen(s);
     w = ;
     for (++i; i < len; i++){
         w = w *  + (s[i] - '');
     }
     if (o){
         cap[n][u] = w;
     }
     else{
         cap[u][n + ] = w;
     }

 }

 void ek_bfs(){
     queue<int> d;
     int s, t, u, v;
     int a[MAXN];
     s = n;
     t = n + ;
     ans = ;
     while (){
         memset(a, , sizeof(a));
         a[s] = INF;
         d.push(s);
         while (!d.empty()){
             u = d.front();
             d.pop();
             for (v = ; v <= n + ; v++){
                 if (a[v] || cap[u][v] <= flow[u][v]) continue;
                 f[v] = u;
                 d.push(v);
                 a[v] = min(a[u] , cap[u][v] - flow[u][v]);
             }
         }
         if (a[t] == ) break;
         for (u = t; u != s; u = f[u]){
             flow[f[u]][u] += a[t];
             flow[u][f[u]] -= a[t];
         }
         ans += a[t];
     }
 }

 int main()
 {
 #ifdef OPEN_FILE
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w", stdout);
 #endif // OPEN_FILE
     int m, np, nc, i, j;
     char s[];
     while (~scanf("%d%d%d%d", &n, &np, &nc, &m)){
         memset(cap, , sizeof(cap));
         memset(flow, , sizeof(flow));
         memset(p, , sizeof(p));
         memset(c, , sizeof(c));
         for (i = ; i <= m; i++){
             scanf("%s", s);
             get_cap(s);
         }
         for (i = ; i <= np; i++){
             scanf("%s", s);
             get_pc(s, p, );
         }
         for (i = ; i <= nc; i++){
             scanf("%s", s);
             get_pc(s, c, );
         }
         ek_bfs();
         printf("%d\n", ans);
     }
 }