poj 3281 Dining (网络流)

/***********************************************
 * Author: fisty
 * Created Time: 2015-08-17 11:09:40
 * File Name   : poj3281.cpp
 *********************************************** */
#include <iostream>
#include <cstring>
#include <deque>
#include <cmath>
#include <queue>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <string>
#include <vector>
#include <cstdio>
#include <bitset>
#include <algorithm>
using namespace std;
#define Debug(x) cout << #x << " " << x <<endl
#define Memset(x, a) memset(x, a, sizeof(x))
const int INF = 0x3f3f3f3f;
typedef long long LL;
typedef pair<int, int> P;
#define FOR(i, a, b) for(int i = a;i < b; i++)
#define lson l, m, k<<1
#define rson m+1, r, k<<1|1
#define MAX_N 410
int N, F, D;
bool likeF[MAX_N][MAX_N];  //食物的喜好
bool likeD[MAX_N][MAX_N];  //饮料的喜好

struct edge{
    int to,cap, rev;
};   
vector<edge> G[MAX_N];
int level[MAX_N];
int iter[MAX_N];

void add_edge(int from, int to, int cap){
    G[from].push_back((edge){to, cap, G[to].size()});
    G[to].push_back((edge){from, 0, G[from].size()-1});
}
void bfs(int s){
    memset(level, -1, sizeof(level));
    queue<int> que;
    level[s] = 0;
    que.push(s);
    while(!que.empty()){
        int v = que.front(); que.pop();
        for(int i = 0;i < G[v].size(); i++){
            edge &e = G[v][i];
            if(e.cap > 0 && level[e.to] < 0){
                level[e.to] = level[v] + 1;
                que.push(e.to);
            }
        }
    }
}
int dfs(int v, int t, int f){
    if(v == t) return f;
    for(int &i = iter[v];i < G[v].size(); i++){
        edge &e = G[v][i];
        if(e.cap > 0 && level[v] < level[e.to]){
            int d = dfs(e.to, t, min(f, e.cap));
            if(d > 0){
                e.cap -= d;
                G[e.to][e.rev].cap += d;
                return d;
            }
        }
    }
    return 0;
}
int max_flow(int s, int t){
    int flow = 0;
    for(;;){
        bfs(s);
        if(level[t] < 0) return flow;
        memset(iter, 0, sizeof(iter));
        int f;
        while((f = dfs(s, t, INF)) > 0){
            flow += f;
        }
    }
}

void solve(){
    //0 ~ N-1 食物一侧的牛
    //N ~ 2*N-1 饮料一侧的牛
    //2*N ~ 2*N + F -1 食物
    //2*N+F ~ 2*N + F + D -1 饮料
    int s = N * 2 + F + D;
    int t = s + 1;

    for(int i = 0;i < F; i++){
        add_edge(s, N * 2 + i, 1);
    }
    for(int i = 0;i < D; i++){
        add_edge(N * 2 + F + i, t , 1);
    }
    for(int i = 0;i < N; i++){
        add_edge(i, N + i, 1);
        for(int j = 0;j < F; j++){
            if(likeF[i][j]){
                add_edge(N * 2 + j, i, 1);
            }
        }
        for(int j = 0;j < D; j++){
            if(likeD[i][j]){
                add_edge(N + i, N * 2 + F + j, 1);
            }
        }
    }
    printf("%d\n", max_flow(s, t));
}
int main() {
    //freopen("in.cpp", "r", stdin);
    //cin.tie(0);
    //ios::sync_with_stdio(false);
    scanf("%d%d%d", &N, &F, &D);
    Memset(likeF, false);
    Memset(likeD, false);
    for(int i = 0;i < N; i++){
        int f, d;
        int x;
        scanf("%d%d", &f, &d);
        for(int j = 0;j < f; j++){
            scanf("%d", &x);
            likeF[i][x-1] = true;
        }
        for(int j = 0;j < d; j++){
            scanf("%d", &x);
            likeD[i][x-1] = true;
        }
    }
    solve();

    return 0;
}