POJ 3436 ACM Computer Factory

最大流+拆点

#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<vector>
#include<queue>
#include<algorithm>
using namespace std;

const int maxn = 2000 + 10;
const int INF = 0x7FFFFFFF;
struct Edge
{
    int from, to, cap, flow;
    Edge(int u, int v, int c, int f) :from(u), to(v), cap(c), flow(f) {}
};
vector<Edge>edges;
vector<int>G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
int n, m, s, t;

void init()
{
    for (int i = 0; i < maxn; i++) G[i].clear();
    edges.clear();
}
void AddEdge(int from, int to, int cap)
{
    edges.push_back(Edge(from, to, cap, 0));
    edges.push_back(Edge(to, from, 0, 0));
    int w = edges.size();
    G[from].push_back(w - 2);
    G[to].push_back(w - 1);
}
bool BFS()
{
    memset(vis, 0, sizeof(vis));
    queue<int>Q;
    Q.push(s);
    d[s] = 0;
    vis[s] = 1;
    while (!Q.empty())
    {
        int x = Q.front();
        Q.pop();
        for (int i = 0; i<G[x].size(); i++)
        {
            Edge e = edges[G[x][i]];
            if (!vis[e.to] && e.cap>e.flow)
            {
                vis[e.to] = 1;
                d[e.to] = d[x] + 1;
                Q.push(e.to);
            }
        }
    }
    return vis[t];
}
int DFS(int x, int a)
{
    if (x == t || a == 0)
        return a;
    int flow = 0, f;
    for (int &i = cur[x]; i<G[x].size(); i++)
    {
        Edge e = edges[G[x][i]];
        if (d[x]+1 == d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0)
        {
            edges[G[x][i]].flow+=f;
            edges[G[x][i] ^ 1].flow-=f;
            flow+=f;
            a-=f;
            if(a==0) break;
        }
    }
    if(!flow) d[x] = -1;
    return flow;
}
int dinic(int s, int t)
{
    int flow = 0;
    while (BFS())
    {
        memset(cur, 0, sizeof(cur));
        flow += DFS(s, INF);
    }
    return flow;
}

int P,N;
int Q[maxn],S[maxn][maxn],D[maxn][maxn];
struct ANS
{
    int a,b,c;
};
vector<ANS>A;

bool ok(int a,int b)
{
    for(int i=1; i<=P; i++)
    {
        if(S[b][i]==0&&D[a][i]==1) return false;
        if(S[b][i]==1&&D[a][i]==0) return false;
    }
    return true;
}

int main()
{
    while(~scanf("%d%d",&P,&N))
    {
        init();
        s=0;
        t=N+N+1;
        for(int i=1; i<=N; i++)
        {
            scanf("%d",&Q[i]);
            for(int j=1; j<=P; j++) scanf("%d",&S[i][j]);
            for(int j=1; j<=P; j++) scanf("%d",&D[i][j]);
        }
        for(int i=1; i<=N; i++) AddEdge(i,i+N,Q[i]);
        for(int i=1; i<=N; i++)
        {
            int j;
            for(j=1; j<=P; j++) if(S[i][j]==1) break;
            if(j==P+1) AddEdge(s,i,INF);
        }

        for(int i=1; i<=N; i++)
        {
            int j;
            for(j=1; j<=P; j++) if(D[i][j]==0) break;
            if(j==P+1) AddEdge(i+N,t,INF);
        }

        for(int i=1; i<=N; i++)
            for(int j=1; j<=N; j++)
                if(ok(i,j))
                    AddEdge(i+N,j,INF);
                    
        int Ans=dinic(s,t);

        printf("%d",Ans);
        A.clear();
        for(int i=0; i<edges.size(); i=i+2)
            if(edges[i].from>=N+1&&edges[i].from<=N+N)
                if(edges[i].to>=1&&edges[i].to<=N)
                    if(edges[i].flow!=0)
                    {
                        ANS e;
                        e.a=edges[i].from-N;
                        e.b=edges[i].to;
                        e.c=edges[i].flow;
                        A.push_back(e);
                    }
        printf(" %d
",A.size());
        for(int i=0; i<A.size(); i++)
            printf("%d %d %d
",A[i].a,A[i].b,A[i].c);
    }
    return 0;
}