HDU 4528 小明系列故事――捉迷藏 (很好的BFS)

#include<cstdio>
#include<cstring>
#include<queue>
#include<iostream>

using namespace std;
const int maxn = 105;

struct Nod{
int x,y,s,t;
};

bool vis[maxn][maxn][4];
char ms[maxn][maxn];
int n,m,t;
queue<Nod> q;
int dx[4] = {1,-1,0,0};
int dy[4] = {0,0,1,-1};

int find(int x,int y){
int res = 0,nx,ny;
for(int i=0;i<4;i++){
nx = x + dx[i];ny = y + dy[i];
while(nx <= n && nx >= 1 && ny <= m && ny >= 1 && ms[nx][ny]=='.'){ nx=nx+dx[i];ny=ny+dy[i]; }
if(nx <= n && nx >= 1 && ny <= m && ny >= 1){
if(ms[nx][ny]=='D') res+=1;
else if(ms[nx][ny]=='E') res+=2;
}
}
return res;
}

int solve(){
//cout<<find(4,5)<<endl;
memset(vis,0,sizeof(vis));
while(!q.empty()) q.pop();
Nod o,ins;
for(int i=1;i<=n;i++)for(int j=1;j<=m;j++)if(ms[i][j]=='S'){
o.x = i;o.y = j;o.s = find(i,j);o.t = 0;
}
q.push(o);
vis[o.x][o.y][o.s] = true;
while(!q.empty()){
o = q.front();q.pop();
if(o.s==3) return o.t;
//printf("%d %d %d %d\n",o.x,o.y,o.s,o.t);
int nx,ny,ns;
for(int i=0;i<4;i++){
nx = o.x + dx[i];ny = o.y + dy[i];
ns = o.s != find(nx,ny) ? o.s + find(nx,ny) : o.s;
if(ns > 3) ns = 3;
if(nx < 1 || nx > n || ny < 1 || ny > m || ms[nx][ny] != '.' || vis[nx][ny][ns]) continue;
ins.x = nx;ins.y = ny;ins.s = ns;ins.t = o.t + 1;
if(ins.t > t) continue;
vis[nx][ny][ns] = true;
q.push(ins);
}
}
return -1;
}

int main(){
int cas;
scanf("%d",&cas);
for(int T = 1 ; T <= cas; T++){
scanf("%d%d%d",&n,&m,&t);
for(int i=1;i<=n;i++) scanf("%s",ms[i]+1);
printf("Case %d:\n%d\n",T,solve());
}
return 0;
}