HDU 2732 Leapin' Lizards

网络最大流+拆点。输出有坑！！！

#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;
};
vector<Edge>edges;
vector<int>G[maxn];
bool vis[maxn];
int d[maxn];
int cur[maxn];
int n,m,s,t;

//求出层次网络
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];
}


//加边
void AddEdge(int from,int to,int cap)
{
    Edge r;
    r.from=from;
    r.to=to;
    r.cap=cap;
    r.flow=0;
    edges.push_back(r);
    Edge d;
    d.from=to;
    d.to=from;
    d.cap=0;
    d.flow=0;
    edges.push_back(d);
    m=edges.size();
    G[from].push_back(m-2);
    G[to].push_back(m-1);
}

//每个阶段来一次DFS增广
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)
        {
            e.flow+=f;
            edges[G[x][i]^1].flow-=f;
            flow+=f;
            a-=f;
            if(a==0) break;
        }
    }
    return flow;
}

//多个阶段，多次建立层次网络。
int Maxflow(int ss,int tt)
{
    int flow=0;
    while(BFS())
    {
        memset(cur,0,sizeof(cur));
        flow+=DFS(ss,INF);
    }
    return flow;
}

int N,M,D,Tot;
char Map1[25][25],Map2[25][25];
int B[25][25];
struct Zhu
{
    int x,y;
    int w;
} zhu[1000];

int main()
{
    int TTT;
    scanf("%d",&TTT);
    for(int YYY=1;YYY<=TTT;YYY++)
    {
        scanf("%d%d",&N,&D);
        memset(B,0,sizeof(B));
        for(int i=0; i<maxn; i++) G[i].clear();
        edges.clear();
        Tot=1;
        for(int i=0; i<N; i++) scanf("%s",Map1[i]);
        for(int i=0; i<N; i++) scanf("%s",Map2[i]);
        M=strlen(Map1[0]);

        for(int i=0; i<N; i++)
            for(int j=0; j<M; j++)
                if(Map1[i][j]!='0')
                {
                    zhu[Tot].x=i;
                    zhu[Tot].y=j;
                    zhu[Tot].w=Map1[i][j]-'0';
                    B[i][j]=Tot;
                    Tot++;
                }
        s=1205;
        t=1206;
        Tot--;
        for(int i=1; i<=Tot; i++)
        {
            int X=zhu[i].x,Y=zhu[i].y;
            AddEdge(i,i+Tot,zhu[i].w);
            if(min(min(X+1,N-X),min(Y+1,M-Y))<=D)
                AddEdge(i+Tot,t,INF);
        }

        for(int i=1; i<=Tot; i++)
            for(int j=1; j<=Tot; j++)
            {
                if(i==j) continue;
                int Ju=abs(zhu[i].x-zhu[j].x)+abs(zhu[i].y-zhu[j].y);
                if(Ju<=D) AddEdge(i+Tot,j,INF);
            }
        int FF=1;
        for(int i=0; i<N; i++)
            for(int j=0; j<M; j++)
                if(Map2[i][j]=='L')
                {
                    AddEdge(s,Tot+Tot+FF,1);
                    AddEdge(Tot+Tot+FF,B[i][j],1);
                    FF++;
                }
        FF--;
        printf("Case #%d: ",YYY);
        int ANS=FF-Maxflow(s,t);
        if(ANS==0) printf("no lizard was left behind.
");
        else if(ANS==1) printf("1 lizard was left behind.
");
        else printf("%d lizards were left behind.
",ANS);
    }
    return 0;
}