HDU 5772 String problem

最大权闭合子图。建图巧妙。

最大权闭合子图：

#pragma comment(linker, "/STACK:1024000000,1024000000")

#include<cstdio>

#include<cstring>

#include<cmath>

#include<algorithm>

#include<vector>

#include<map>

#include<set>

#include<queue>

#include<stack>

#include<iostream>

using namespace std;

typedef long long LL;

const double pi=acos(-1.0),eps=1e-;

void File()

{

    freopen("D:\\in.txt","r",stdin);

    freopen("D:\\out.txt","w",stdout);

}

inline int read()

{

    char c = getchar();  while(!isdigit(c)) c = getchar();

    int x = ;

    while(isdigit(c)) { x = x *  + c - ''; c = getchar(); }

    return x;

}

const int maxn =  + ;

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 = ; i < maxn; i++) G[i].clear();

    edges.clear();

}

void AddEdge(int from, int to, int cap)

{

    edges.push_back(Edge(from, to, cap, ));

    edges.push_back(Edge(to, from, , ));

    int w = edges.size();

    G[from].push_back(w - );

    G[to].push_back(w - );

}

bool BFS()

{

    memset(vis, , sizeof(vis));

    queue<int>Q;

    Q.push(s);

    d[s] = ;

    vis[s] = ;

    while (!Q.empty())

    {

        int x = Q.front();

        Q.pop();

        for (int i = ; i<G[x].size(); i++)

        {

            Edge e = edges[G[x][i]];

            if (!vis[e.to] && e.cap>e.flow)

            {

                vis[e.to] = ;

                d[e.to] = d[x] + ;

                Q.push(e.to);

            }

        }

    }

    return vis[t];

}

int DFS(int x, int a)

{

    if (x == t || a == )

        return a;

    int flow = , f;

    for (int &i = cur[x]; i<G[x].size(); i++)

    {

        Edge e = edges[G[x][i]];

        if (d[x]+ == d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>)

        {

            edges[G[x][i]].flow+=f;

            edges[G[x][i] ^ ].flow-=f;

            flow+=f;

            a-=f;

            if(a==) break;

        }

    }

    if(!flow) d[x] = -;

    return flow;

}

int dinic(int s, int t)

{

    int flow = ;

    while (BFS())

    {

        memset(cur, , sizeof(cur));

        flow += DFS(s, INF);

    }

    return flow;

}

const int MAXM=;

int T,len,a[MAXM],b[MAXM],w[MAXM][MAXM],val[*MAXM*MAXM],ans;

char str[MAXM];

int main()

{

    scanf("%d",&T); int cas=;

    while(T--)

    {

        scanf("%d",&len); scanf("%s",str);

        for(int i=;i<;i++) scanf("%d%d",&a[i],&b[i]);

        for(int i=;i<len;i++) for(int j=;j<len;j++) scanf("%d",&w[i][j]);

        init(); ans=;

        s=len*len+len+; val[s]=;

        t=len*len+len++; val[t]=;

        for(int i=;i<len;i++) for(int j=i+;j<len;j++)

        {

            val[i*len+j]=w[i][j]+w[j][i];

            AddEdge(i*len+j,len*len+i,INF);

            AddEdge(i*len+j,len*len+j,INF);

            if(val[i*len+j]>) AddEdge(s,i*len+j,val[i*len+j]), ans=ans+val[i*len+j];

            else if(val[i*len+j]<) AddEdge(i*len+j,t,-val[i*len+j]);

        }

        for(int i=len*len;i<=len*len+len-;i++)

        {

            val[i]=-a[str[i-len*len]-''];

            AddEdge(i,len*len+len+str[i-len*len]-'',INF);

            if(val[i]>) AddEdge(s,i,val[i]), ans=ans+val[i];

            else if(val[i]<) AddEdge(i,t,-val[i]);

        }

        for(int i=len*len+len;i<=len*len+len+-;i++)

        {

            val[i]=-b[i-(len*len+len)]+a[i-(len*len+len)];

            if(val[i]>) AddEdge(s,i,val[i]), ans=ans+val[i];

            else if(val[i]<) AddEdge(i,t,-val[i]);

        }

        ans=ans-dinic(s,t);

        printf("Case #%d: %d\n",cas++,ans);

    }

    return ;

}