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 = 105;
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 = 0;
    for (i = 1; s[i] != ','; i++){
        u = u * 10 + (s[i] - '0');
    }
    v = 0;
    for (++i; s[i] != ')'; i++){
        v = v * 10 + (s[i] - '0');
    }
    int len = strlen(s);
    w = 0;
    for (++i; i < len; i++){
        w = w * 10 + (s[i] - '0');
    }
    cap[u][v] = w;
}

void get_pc(char s[], int* t, int o)
{
    int i, u, w;
    u = 0;
    for (i = 1; s[i] != ')'; i++){
        u = u * 10 + (s[i] - '0');
    }
    int len = strlen(s);
    w = 0;
    for (++i; i < len; i++){
        w = w * 10 + (s[i] - '0');
    }
    if (o){
        cap[n][u] = w;
    }
    else{
        cap[u][n + 1] = w;
    }
    
}

void ek_bfs(){
    queue<int> d;
    int s, t, u, v;
    int a[MAXN];
    s = n;
    t = n + 1;
    ans = 0;
    while (1){
        memset(a, 0, sizeof(a));
        a[s] = INF;
        d.push(s);
        while (!d.empty()){
            u = d.front();
            d.pop();
            for (v = 0; v <= n + 1; 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] == 0) 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[101];
    while (~scanf("%d%d%d%d", &n, &np, &nc, &m)){
        memset(cap, 0, sizeof(cap));
        memset(flow, 0, sizeof(flow));
        memset(p, 0, sizeof(p));
        memset(c, 0, sizeof(c));
        for (i = 1; i <= m; i++){
            scanf("%s", s);
            get_cap(s);
        }
        for (i = 1; i <= np; i++){
            scanf("%s", s);
            get_pc(s, p, 1);
        }
        for (i = 1; i <= nc; i++){
            scanf("%s", s);
            get_pc(s, c, 0);
        }
        ek_bfs();
        printf("%d
", ans);
    }
}