poj 3281 Dining

原题链接：http://poj.org/problem?id=3281
最大流，拆点构图。

#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<queue>#include<map>using std::min;using std::sort;using std::pair;using std::swap;using std::queue;using std::vector;using std::multimap;#define pb(e) push_back(e)#define sz(c) (int)(c).size()#define mp(a, b) make_pair(a, b)#define all(c) (c).begin(), (c).end()#define iter(c) __typeof((c).begin())#define cls(arr, val) memset(arr, val, sizeof(arr))#define cpresent(c, e) (find(all(c), (e)) != (c).end())#define rep(i, n) for(int i = 1; i <= (int)n; i++)#define tr(c, i) for(iter(c) i = (c).begin(); i != (c).end(); ++i)const int Max_N = 1100;const int INF = 0x3f3f3f3f;struct Ford_Fulkerson {    struct edge { int to, cap, next, rev; }G[Max_N << 2];    int  N, F, D, tot, head[Max_N];    bool vis[Max_N], Food[Max_N][Max_N], Drink[Max_N][Max_N];    inline void init(int n, int f, int d) {        tot = 0;        this->N = n, this->F = f, this->D =d;        cls(head, -1), cls(Food, false), cls(Drink, false);    }    inline void add_edge(int u, int v, int cap = 1) {        G[tot] = (edge){ v, cap, head[u], tot + 1 }; head[u] = tot++;        G[tot] = (edge){ u,   0, head[v], tot - 1 }; head[v] = tot++;    }    inline void built() {        int x, y, v;        rep(i, N) {            scanf("%d %d", &x, &y);            while(x--) {                scanf("%d", &v);                Food[i][v] = true;            }            while(y--) {                scanf("%d", &v);                Drink[i][v] = true;            }        }    }    inline int dfs(int u, int t, int f) {        if(u == t) return f;        vis[u] = true;        for(int i = head[u]; ~i; i = G[i].next) {            edge &e = G[i];            if(e.cap > 0 && !vis[e.to]) {                int d = dfs(e.to, t, min(e.cap, f));                if(d > 0) {                    e.cap -= d;                    G[e.rev].cap +=d;                    return d;                }            }        }        return 0;    }    inline void max_flow(int s, int t) {        int flow = 0;        while(true) {            cls(vis, false);            int f = dfs(s, t, INF);            if(!f) break;            flow += f;        }        printf("%d\n", flow);    }    inline void solve() {        int s = 1, t = s + F + 2 * N + D + 1;        rep(i, F) {            add_edge(s, s + i);        }        rep(i, D) {            add_edge(s + F + 2 * N + i, t);        }        rep(i, N) {            add_edge(s + F + i, s + F + N + i, 1);            rep(j, F) {                if(Food[i][j]) add_edge(s + j, s + F + i);            }            rep(j, D) {                if(Drink[i][j]) add_edge(s + F + N + i, s + F + 2 * N + j);            }        }        max_flow(s, t);    }}go;int main() {#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    int n, f, d;    while(~scanf("%d %d %d", &n, &f, &d)) {        go.init(n ,f ,d);        go.built();        go.solve();    }    return 0;}