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[][];

struct node{
    int x,y,step;
    friend bool operator <(node a,node b){
        return a.step>b.step;
    }
};

int dx[]={,-,,};
int dy[]={,,,-};
int vis[][];

int rd[][];

int bfs(){
    memset(vis,,sizeof(vis));
    priority_queue <node> q;
    node s;
    s.x=;s.y=;s.step=;
    if(M[][]!='X' && M[n-][m-]!='X')q.push(s);
    while(!q.empty()){
        node u=q.top();
        q.pop();
        if(u.x==n- && u.y==m-)return u.step;
        for(int i=;i<;i++){
            int xx=u.x+dx[i];
            int yy=u.y+dy[i];
            if(xx< || xx>=n || yy< || yy>=m)continue;
            if(M[xx][yy]=='X')continue;
            if(vis[xx][yy])continue;
            vis[xx][yy]=;
            node next=u;
            next.x=xx;next.y=yy;next.step++;
            if(M[xx][yy]>='' && M[xx][yy]<='')
                next.step+=(M[xx][yy]-'');
            rd[xx][yy]=i;
            q.push(next);
        }
    }
    return INF;
}
int tt;
void output(int x,int y){
    if(rd[x][y]==-)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]>='' && M[x][y]<=''){
        int nn=M[x][y]-'';
        while(nn--){
            printf("%ds:FIGHT AT (%d,%d)\n",tt++,x,y);
        }
    }
}

int main(){
    while(~scanf("%d%d",&n,&m)){
        for(int i=;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[][]=-;
            tt=;
            output(n-,m-);
           }
           puts("FINISH");
    }
    return ;
}