POJ-2584 T-Shirt Gumbo 最大流

简单构图，构造一个S流向 S,M,L,X,T，赛事 T1,T2,T2...TN流向汇点T。

代码如下：

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#define INF 0x3f3f3f3f
#define MAXN 25
using namespace std;

int N, cap[40][40], flow[40][40], p[40], c[40], S = 0, T = 38;

int hash[130], maxflow;

void init()
{
    maxflow = 0;
    memset(cap, 0, sizeof (cap));
    memset(flow, 0, sizeof (flow));
    memset(p, 0xff, sizeof (p));
}

inline int min(int x, int y)
{
    return x < y ? x : y;
}

void bfs()
{
    int finish = 0, pos;
    while (!finish) {
        memset(c, 0, sizeof (c));
        c[S] = INF;
        queue<int>q;
        q.push(S);
        while (!q.empty()) {
            if (c[T]) {
                break;
            }
            pos = q.front();
            q.pop();
            for (int i = 1; i <= T; ++i) {
                if (!c[i] && cap[pos][i] > flow[pos][i]) {
                    c[i] = min(c[pos], cap[pos][i] - flow[pos][i]);
                    p[i] = pos;
                    q.push(i);
                }
            }
        }
        maxflow += c[T];
        if (!c[T]) {
            finish = 1;
            continue;
        }
        pos = T;
        while (pos != 0) {
            flow[p[pos]][pos] += c[T];
            flow[pos][p[pos]] -= c[T];
            pos = p[pos];
        }
    }
}

int main()
{
    char op[20], detail[5];
    int x;
    hash['S'] = 1, hash['M'] = 2, hash['L'] = 3, hash['X'] = 4, hash['T'] = 5;
    while (scanf("%s", op), strcmp(op, "ENDOFINPUT")) {
        init();
        scanf("%d", &N);
        for (int i = 1; i <= N; ++i) {
            scanf("%s", detail);
            for (int j = hash[detail[0]]; j <= hash[detail[1]]; ++j) {
                cap[j][5+i] = INF; // 反向边已经清零
                cap[5+i][T] = 1;
            }
        }
        for (int i = 1; i <= 5; ++i) {
            scanf("%d", &x);
            cap[S][i] = x;
        }
        scanf("%s", op);
        bfs();
        if (maxflow == N) {
            puts("T-shirts rock!");
        }
        else {
            puts("I'd rather not wear a shirt anyway...");
        }
    }
    return 0;
}