HDU 4634 Swipe Bo （搜索）

注意；UDLR可能构成一个死循环。UDLR正好指向旁边的墙壁，则不能再移动了。

普通的最短路。做题的时候太疲劳了。wa了n次。

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <cmath>#include <stack>#include <map>#include <string>#define LL long long#define DB double#define SF scanf#define SI(a) scanf("%d",&a)#define SD(a) scanf("%lf",&a)#define PF printf#define MM(a,b) memset(a,b,sizeof(a))#define N 209#define bug cout<<"bug"<<endlusing namespace std;const int INF = 0x3f3f3f3f;char ch[N][N];struct sty{    int key,x,y;    sty(int a=0,int b=0,int k=0)    {        x = a;y = b;key = k;    }    int operator<(const sty t)const    {        if(key!=t.key) return key-t.key;        if(x!=t.x) return x-t.x;        return y-t.y;    }}ext,start;//map<sty,int> mp;int n,m;bool oor(int x,int y){    if(x<0||x>=n) return false;    if(y<0||y>=m) return false;    return true;}int kkey[N][N];void fin(){    int tmp = 0;    for(int i=0;i<n;i++)    for(int j=0;j<m;j++)    {        if(ch[i][j]=='K')        {            kkey[i][j] = tmp;            tmp++;        }else        {            kkey[i][j] = -1;        }        if(ch[i][j]=='E')        {            ext.x = i;            ext.y = j;           // bug;        }        if(ch[i][j]=='S')        {            start.key = 0;            start.x = i;            start.y = j;        }    }    ext.key = (1<<tmp)-1;}queue<sty> que;int dis[N][N][1<<7];int dx[]={0,0,-1,1};int dy[]={-1,1,0,0};int ANS;int visit[N][N];sty get(sty e,int k){    if(visit[e.x][e.y]>3) return start;    sty t = e;    int v=e.key;    for(int i=1;;i++)    {        int tx = e.x+dx[k]*i,ty = e.y+dy[k]*i;        if(ch[tx][ty]=='K')        {            v|=(1<<kkey[tx][ty]);        }        if(!oor(tx,ty)) return start;        if(ch[tx][ty]=='#') return t;        t.x = tx;t.y = ty;        t.key = v;        if(t.x==ext.x&&t.y==ext.y&&t.key==ext.key)        {            return t;        }        if(ch[tx][ty]=='L')        {            visit[tx][ty]++;            sty ret= get(t,0);            visit[tx][ty]--;            return ret;        }else if(ch[tx][ty]=='R')        {            visit[tx][ty]++;            sty ret= get(t,1);            visit[tx][ty]--;            return ret;        }else if(ch[tx][ty]=='U')        {            visit[tx][ty]++;            sty ret= get(t,2);            visit[tx][ty]--;            return ret;        }else if(ch[tx][ty]=='D')        {            visit[tx][ty]++;            sty ret= get(t,3);            visit[tx][ty]--;            return ret;        }    }}int solve(){    fin();   // cout<<"ext "<<ext.x<<" "<<ext.y<<" "<<ext.key<<endl;    while(!que.empty()) que.pop();    que.push(start);    sty e,t;    memset(dis,INF,sizeof(dis));    dis[start.x][start.y][start.key] = 0;    //mp[start] = 1;    while(!que.empty())    {        e = que.front();que.pop();       // cout<<e.x<<" "<<e.y<<endl;        for(int i=0;i<4;i++)        {            if(ch[e.x][e.y]=='L'||ch[e.x][e.y]=='D'||ch[e.x][e.y]=='U'||ch[e.x][e.y]=='R')            continue;            t = get(e,i);            if(dis[t.x][t.y][t.key]!=INF) continue;            que.push(t);           // mp[t] = 1;          //  cout<<t.x<<" "<<t.y<<" "<<t.key<<" dis = "<<dis[e.x][e.y][e.key]+1<<endl;            dis[t.x][t.y][t.key] = dis[e.x][e.y][e.key]+1;        }    }    if(dis[ext.x][ext.y][ext.key]==INF) return -1;    return dis[ext.x][ext.y][ext.key];}int main(){       while(~SF("%d%d",&n,&m))    {        for(int i=0;i<n;i++)        {            SF("%s",ch[i]);        }        PF("%d\n",solve());    }    return 0;}