HDU-1226 超级密码 （BFS+剪枝）

 1 # include<iostream>
 2 # include<cstdio>
 3 # include<string>
 4 # include<queue>
 5 # include<cstring>
 6 # include<algorithm>
 7 using namespace std;
 8 struct node
 9 {
10     string ans;
11     int val;
12     node(string s,int m):ans(s),val(m){}
13     bool operator < (const node &a) const {
14         if(ans.size()==a.ans.size())
15             return ans>a.ans;
16         return ans.size()>a.ans.size();
17     }
18 };
19 int vis[5005],n,m,c,num[20];
20 int get()
21 {
22     char ch;
23     cin>>ch;
24     if(ch>=‘0‘&&ch<=‘9‘)
25         return ch-‘0‘;
26     return ch-‘A‘+10;
27 }
28 void bfs()
29 {
30     memset(vis,0,sizeof(vis));
31     priority_queue<node>q;
32     for(int i=0;i<m;++i){
33         if(num[i]==0)
34             continue;
35         string s;
36         if(num[i]<=9)
37             s+=num[i]+‘0‘;
38         else
39             s+=num[i]-10+‘A‘;
40         vis[num[i]%n]=1;
41         q.push(node(s,num[i]%n));
42     }
43     while(!q.empty())
44     {
45         node u=q.top();
46         q.pop();
47         if(u.val==0){
48             cout<<u.ans<<endl;
49             return ;
50         }
51         if(u.ans.size()>=500)
52             continue;
53         for(int i=0;i<m;++i){
54             int now=(u.val*c+num[i])%n;
55             if(vis[now])
56                 continue;
57             string s=u.ans;
58             if(num[i]<=9)
59                 s+=num[i]+‘0‘;
60             else
61                 s+=num[i]-10+‘A‘;
62             vis[now]=1;
63             q.push(node(s,now));
64         }
65     }
66     printf("give me the bomb please\n");
67 }
68 int main()
69 {
70     int T;
71     scanf("%d",&T);
72     while(T--)
73     {
74         scanf("%d%d",&n,&c);
75         scanf("%d",&m);
76         for(int i=0;i<m;++i)
77             num[i]=get();
78         sort(num,num+m);
79         if(n==0){
80             if(num[0]==0)
81                 printf("0\n");
82             else
83                 printf("give me the bomb please\n");
84             continue;
85         }
86         bfs();
87     }
88     return 0;
89 }

 1 # include<iostream>
 2 # include<cstdio>
 3 # include<string>
 4 # include<cstring>
 5 # include<algorithm>
 6 using namespace std;
 7 int vis[5005],n,m,c,num[20],flag;
 8 string aans;
 9 int get()
10 {
11     char ch;
12     cin>>ch;
13     if(ch>=‘0‘&&ch<=‘9‘)
14         return ch-‘0‘;
15     return ch-‘A‘+10;
16 }
17 bool is_smaller(string s1,string s2)
18 {
19     if(s1.size()<s2.size())
20         return true;
21     if(s1.size()==s2.size()&&s1<s2)
22         return true;
23     return false;
24 }
25 void dfs(string ans,int s)
26 {
27     if(ans.size()>500)
28         return ;
29     if(s==0){
30         if(!flag){
31             aans=ans;
32             flag=1;
33         }
34         else{
35             if(is_smaller(ans,aans))
36                 aans=ans;
37         }
38         return ;
39     }
40     //cout<<ans<<endl;
41     if(flag){
42         if(aans.size()<ans.size())
43             return ;
44         if(aans.size()==ans.size()&&ans>aans)
45             return ;
46     }
47     string temp=ans;
48     for(int i=0;i<m;++i){
49         int ns=(s*c+num[i])%n;
50         if(vis[ns])
51             continue;
52         if(num[i]<=9)
53             ans+=num[i]+‘0‘;
54         else
55             ans+=num[i]+‘A‘-10;
56         vis[ns]=1;
57         dfs(ans,ns);
58         vis[ns]=0;
59         ans=temp;
60     }
61 }
62 int main()
63 {
64     int T;
65     scanf("%d",&T);
66     while(T--)
67     {
68         scanf("%d%d",&n,&c);
69         scanf("%d",&m);
70         for(int i=0;i<m;++i)
71             num[i]=get();
72         sort(num,num+m);
73         flag=0;
74         memset(vis,0,sizeof(vis));
75         for(int i=0;i<m;++i){
76             //cout<<num[i]<<endl;
77             string ans;
78             if(num[i]==0)
79                 continue;
80             if(num[i]<=9)
81                 ans+=num[i]+‘0‘;
82             else
83                 ans+=num[i]-10+‘A‘;
84             if(num[i]%n==0){
85                 aans=ans;
86                 flag=1;
87                 break;
88             }
89             vis[num[i]%n]=1;
90             dfs(ans,num[i]%n);
91             vis[num[i]%n]=0;
92         }
93         if(!flag)
94             printf("give me the bomb please\n");
95         else
96             cout<<aans<<endl;
97     }
98     return 0;
99 }