【双向bfs】2017多校训练十 HDU 6171 Admiral

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 typedef unsigned long long ull;
 5 const int inf=0x3f3f3f3f;
 6 struct node
 7 {
 8     int val[6][6];
 9     int tp;
10     int r;
11     int c;
12     int step;
13 }s,t;
14 
15 ull Hash(node t)
16 {
17     ull tmp=0;
18     for(int i=0;i<6;i++)
19     {
20         for(int j=0;j<=i;j++)
21         {
22             tmp=tmp*6+t.val[i][j];
23         }
24     }
25     return tmp;
26 }
27 queue<node> Q;
28 map<ull,int> book[2]; 
29 int dir[4][2]={{1,0},{-1,0},{1,1},{-1,-1}};
30 int bfs(node s,node t)
31 {
32     while(!Q.empty()) Q.pop();
33     book[0].clear();
34     book[1].clear();
35     s.step=t.step=0;
36     s.tp=0;t.tp=1;
37     book[s.tp][Hash(s)]=0;
38     book[t.tp][Hash(t)]=0;
39     Q.push(s);Q.push(t);
40     while(!Q.empty())
41     {
42         node q=Q.front(),e;Q.pop();
43         ull tmp=Hash(q);
44         if(book[!q.tp].count(tmp))
45         {
46             if(book[!q.tp][tmp]+q.step<=20) 
47                 return book[!q.tp][tmp]+q.step;
48             else continue;
49         }
50         if(q.step>=10) continue;
51         for(int i=0;i<4;i++)
52         {
53             e=q;
54             e.r+=dir[i][0];
55             e.c+=dir[i][1];
56             if(e.r<0||e.r>=6||e.c<0||e.c>=6||e.c>e.r) continue;
57             swap(e.val[e.r][e.c],e.val[q.r][q.c]);
58             ull tmp=Hash(e);
59             if(book[e.tp].count(tmp)) continue;
60             book[e.tp][tmp]=++e.step;
61             Q.push(e);
62         }
63     }
64     return inf;
65 }
66 int main()
67 {
68     int T;
69     scanf("%d",&T);
70     while(T--)
71     {
72         for(int i=0;i<6;i++)
73         {
74             for(int j=0;j<=i;j++)
75             {
76                 scanf("%d",&s.val[i][j]);
77                 if(s.val[i][j]==0)
78                 {
79                     s.r=i;s.c=j;
80                 }
81                 t.val[i][j]=i;
82             }
83         }
84         t.r=t.c=0;
85         int ans=bfs(s,t);
86         if(ans==inf) puts("too difficult");
87         else printf("%d\n",ans);
88     }
89     return 0;
90  }