题目链接：http://icpc.njust.edu.cn/Problem/Hdu/1242/
这次的迷宫是有守卫的，杀死一个守卫需要花费1个单位的时间，所以以走的步数为深度，在每一层进行搜索，由于走一步的花费不一定是1，所以我们需要用优先队列寻找最优值。这个题目真是模板题。
代码如下：
1 #include<bits/stdc++.h> 2 using namespace std; 3 typedef unsigned int ui; 4 typedef long long ll; 5 typedef unsigned long long ull; 6 #define pf printf 7 #define mem(a,b) memset(a,b,sizeof(a)) 8 #define prime1 1e9+7 9 #define prime2 1e9+9 10 #define pi 3.14159265 11 #define lson l,mid,rt<<1 12 #define rson mid+1,r,rt<<1|1 13 #define scand(x) scanf("%llf",&x) 14 #define f(i,a,b) for(int i=a;i<=b;i++) 15 #define scan(a) scanf("%d",&a) 16 #define dbg(args) cout<<#args<<":"<<args<<endl; 17 #define inf 0x3f3f3f3f 18 #define maxn 205 19 int n,m,t; 20 int sx,sy,tx,ty; 21 bool vis[maxn][maxn]; 22 char Map[maxn][maxn]; 23 int dir[][2]={0,1,0,-1,1,0,-1,0}; 24 struct node{ 25 int x,y,time; 26 node(int x,int y,int s):x(x),y(y),time(s){} 27 node(){} 28 friend operator< (node a,node b) 29 { 30 return a.time>b.time;//逆定义运算符 31 } 32 }; 33 int ans=0; 34 node cur,nxt; 35 void bfs() 36 { 37 priority_queue<node>q; 38 q.push(node(sx,sy,0)); 39 vis[sx][sy]=1; 40 while(!q.empty()) 41 { 42 cur=q.top(); 43 q.pop(); 44 if(cur.x==tx&&cur.y==ty) 45 { 46 ans=cur.time; 47 return; 48 } 49 f(i,0,3) 50 { 51 nxt=cur; 52 nxt.x+=dir[i][0]; 53 nxt.y+=dir[i][1]; 54 nxt.time++; 55 if(nxt.x<1||nxt.x>n||nxt.y<1||nxt.y>m||Map[nxt.x][nxt.y]=='#')continue; 56 if(vis[nxt.x][nxt.y])continue; 57 vis[nxt.x][nxt.y]=1; 58 if(Map[nxt.x][nxt.y]=='x')nxt.time++; 59 q.push(nxt); 60 } 61 } 62 } 63 int main() 64 { 65 //freopen("input.txt","r",stdin); 66 //freopen("output.txt","w",stdout); 67 std::ios::sync_with_stdio(false); 68 while(scanf("%d%d",&n,&m)!=EOF) 69 { 70 ans=0; 71 mem(vis,false); 72 f(i,1,n) 73 f(j,1,m) 74 { 75 scanf(" %c",&Map[i][j]); 76 if(Map[i][j]=='r')sx=i,sy=j; 77 if(Map[i][j]=='a')tx=i,ty=j; 78 } 79 bfs(); 80 if(!ans)pf("Poor ANGEL has to stay in the prison all his life. "); 81 else pf("%d ",ans); 82 } 83 84 }