HDU 1026

http://acm.hdu.edu.cn/showproblem.php?pid=1026

记录bfs路径，用一个数组记录next前驱的方向，然后递归的时候减回去即可

#include <iostream>

#include <cstdio>

#include <cstring>

#include <queue>



using namespace std ;

const int INF=0xfffffff;



int n,m;

char M[105][105];



struct node{

    int x,y,step;

    friend bool operator <(node a,node b){

        return a.step>b.step;

    }

};



int dx[]={1,-1,0,0};

int dy[]={0,0,1,-1};

int vis[105][105];



int rd[105][105];



int bfs(){

    memset(vis,0,sizeof(vis));

    priority_queue <node> q;

    node s;

    s.x=0;s.y=0;s.step=0;

    if(M[0][0]!='X' && M[n-1][m-1]!='X')q.push(s);

    while(!q.empty()){

        node u=q.top();

        q.pop();

        if(u.x==n-1 && u.y==m-1)return u.step;

        for(int i=0;i<4;i++){

            int xx=u.x+dx[i];

            int yy=u.y+dy[i];

            if(xx<0 || xx>=n || yy<0 || yy>=m)continue;

            if(M[xx][yy]=='X')continue;

            if(vis[xx][yy])continue;

            vis[xx][yy]=1;

            node next=u;

            next.x=xx;next.y=yy;next.step++;

            if(M[xx][yy]>='1' && M[xx][yy]<='9')

                next.step+=(M[xx][yy]-'0');

            rd[xx][yy]=i;

            q.push(next);

        }

    }

    return INF;

}

int tt;

void output(int x,int y){

    if(rd[x][y]==-1)return;

    int xx=x-dx[rd[x][y]];

    int yy=y-dy[rd[x][y]];

    output(xx,yy);

    printf("%ds:(%d,%d)->(%d,%d)\n",tt++,xx,yy,x,y);

    if(M[x][y]>='1' && M[x][y]<='9'){

        int nn=M[x][y]-'0';

        while(nn--){

            printf("%ds:FIGHT AT (%d,%d)\n",tt++,x,y);

        }

    }

}



int main(){

    while(~scanf("%d%d",&n,&m)){

        for(int i=0;i<n;i++)    

            scanf("%s",M[i]);

           int ans=bfs();

           if(ans==INF)puts("God please help our poor hero.");

           else{

               printf("It takes %d seconds to reach the target position, let me show you the way.\n",ans);

            rd[0][0]=-1;

            tt=1;

            output(n-1,m-1);

           }

           puts("FINISH");

    }

    return 0;

}

View Code