HDU 3468 Treasure Hunting

类似二分图。匹配之类的。。

//author: CHC
//First Edit Time:	2014-08-16 18:54
//Last Edit Time:	2014-08-16 19:20
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <set>
#include <vector>
#include <map>
#include <queue>
#include <set>
#include <algorithm>
#include <limits.h>
using namespace std;
typedef long long LL;
const int MAXN=1e+5;
const int MAXM=1e+6;
const int INF = INT_MAX;
struct Edge
{
    int from,to,ci,next;
    Edge(){}
    Edge(int _from,int _to,int _ci,int _next):from(_from),to(_to),ci(_ci),next(_next){}
}e[MAXM];
int head[MAXN],tot;
int dis[MAXN];
int top,sta[MAXN],cur[MAXN];
inline void init(){
    memset(head,-1,sizeof(head));
    tot=0;
}
inline void AddEdge(int u,int v,int ci0,int ci1=0){
    e[tot]=Edge(u,v,ci0,head[u]);
    head[u]=tot++;
    e[tot]=Edge(v,u,ci1,head[v]);
    head[v]=tot++;
}
inline bool bfs(int st,int et){
    memset(dis,0,sizeof(dis));
    dis[st]=1;
    queue <int> q;
    q.push(st);
    while(!q.empty()){
        int now=q.front();
        q.pop();
        for(int i=head[now];i!=-1;i=e[i].next){
            int next=e[i].to;
            if(e[i].ci&&!dis[next]){
                dis[next]=dis[now]+1;
                if(next==et)return true;
                q.push(next);
            }
        }
    }
    return false;
}
LL Dinic(int st,int et){
    LL ans=0;
    while(bfs(st,et)){
        //printf("here\n");
        top=0;
        memcpy(cur,head,sizeof(head));
        int u=st,i;
        while(1){
            if(u==et){
                int pos,minn=INF;
                //printf("top:%d\n",top);
                for(i=0;i<top;i++)
                {
                    if(minn>e[sta[i]].ci){
                        minn=e[sta[i]].ci;
                        pos=i;
                    }
                    //printf("%d --> %d\n",e[sta[i]].from,e[sta[i]].to);
                }
                for(i=0;i<top;i++){
                    e[sta[i]].ci-=minn;
                    e[sta[i]^1].ci+=minn;
                }
                top=pos;
                u=e[sta[top]].from;
                ans+=minn;
                //printf("minn:%d\n\n",minn);
            }
            for(i=cur[u];i!=-1;cur[u]=i=e[i].next)
                if(e[i].ci&&dis[u]+1==dis[e[i].to])break;
            if(cur[u]!=-1){
                sta[top++]=cur[u];
                u=e[cur[u]].to;
            }
            else {
                if(top==0)break;
                dis[u]=0;
                u=e[sta[--top]].from;
            }
        }
    }
    return ans;
}
struct point
{
    char pos;
    int x,y;
    point(){}
    point(char _pos,int _x,int _y):pos(_pos),x(_x),y(_y){}
}cs[110];
bool cmp(point x,point y){
    return x.pos<y.pos;
}
char map1[110][110];
int disx[2][110][110],n,m;
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};
int bfs(point st,point et,int fl){
    pair <int,int> now,next;
    queue < pair<int,int> > q;
    q.push(pair<int,int>(st.x,st.y));
    memset(disx[fl],-1,sizeof(disx[fl]));
    disx[fl][st.x][st.y]=0;
    while(!q.empty()){
        now=q.front();
        q.pop();
        if(now.first==et.x&&now.second==et.y)return disx[fl][now.first][now.second];
        for(int i=0;i<4;i++){
            next.first=now.first+dx[i];
            next.second=now.second+dy[i];
            if(next.first<1||next.first>n||next.second<1||next.second>m)continue;
            if(map1[next.first][next.second]=='#')continue;
            if(disx[fl][next.first][next.second]!=-1)continue;
            disx[fl][next.first][next.second]=disx[fl][now.first][now.second]+1;
            q.push(next);
        }
    }
    return -1;
}
int main()
{
    while(~scanf("%d%d",&n,&m)){
        int tos1=0;
        init();
        for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++){
            scanf(" %c",&map1[i][j]);
            if(map1[i][j]!='.'&&map1[i][j]!='*'&&map1[i][j]!='#'){
                cs[tos1++]=point(map1[i][j],i,j);
            }
        }
        //printf("tos1:%d\n",tos1);
        sort(cs,cs+tos1,cmp);
        int flag=1;
        for(int i=0;i<tos1-1&&flag;i++){
            int t1=bfs(cs[i],cs[i+1],0);
            int t2=bfs(cs[i+1],cs[i],1);
            //printf("%c-->%c\n",cs[i].pos,cs[i+1].pos);
            if(t1==-1){ flag=0;break; }
            for(int ii=1;ii<=n;ii++)
            for(int jj=1;jj<=m;jj++)
                if(disx[0][ii][jj]!=-1&&disx[1][ii][jj]!=-1)
                if(disx[0][ii][jj]+disx[1][ii][jj]==t1){
                if(map1[ii][jj]=='*'){
                    AddEdge(ii*m+jj+200,cs[i+1].pos,1);
                    //printf("%d %d --> %c\n",ii,jj,cs[i+1].pos);
                }
                }
        }
        if(flag){
            for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
                AddEdge(0,i*m+j+200,1);
            for(int i=0;i<tos1;i++)
                AddEdge(cs[i].pos,1,1);
            printf("%I64d\n",Dinic(0,1));
        }
        else puts("-1");
    }
    return 0;
}
/*
2 4
.#B.
*A*C
 */