PKU 3185 The Water Bowls

不喜欢模拟,直接BFS+位压缩保存状态~300+ms还是可以接受的

虽然模拟是0ms...囧~

1. #include <iostream>
2. #include <list>
3. #include <map>
4. #include <cmath>
5. #include <algorithm>
6. #include <bitset>
7. #include <queue>
8. #include <stack>
9. #include <vector>
10. using namespace std;
11. bool hash[1048576];
12. int c[21]={0,1};
13. struct state
14. {
15.     int water,t;
16. }tmp,p;
17. queue<state> q;
18. int main()
19. {
20.     int i,hash_tmp=0,t,res=0;
21.     for(i=2;i<=20;i++)c[i]=c[i-1]*2;
22.     for(i=1;i<=20;i++)scanf("%d",&t),hash_tmp=2*hash_tmp+t;
23.     memset(hash,false,sizeof(hash));
24.     hash[hash_tmp]=true;
25.     tmp.water=hash_tmp;tmp.t=0;
26.     if(tmp.water==0)cout<<0<<endl;
27.     else{
28.     q.push(tmp);
29.     while(!q.empty())
30.         {
31.             tmp=q.front();tmp.t++;
32.             for(i=1;i<=20;i++)
33.                 {
34.                     p=tmp;
35.                             p.water^=c[i];
36.                             if(i-1>=1)p.water^=c[i-1];
37.                             if(i+1<=20)p.water^=c[i+1];
38.                             if(hash[p.water])continue;
39.                             q.push(p);
40.                             hash[p.water]=true;
41.                             if(p.water==0)break;
42.                 }
43.             q.pop();
44.             if(p.water==0)break;
45.         }   
46.     printf("%d/n",p.t);
47.     }
49.     return 0;
50. }