UVA690-Pipeline Scheduling(dfs+二进制压缩状态)

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 
 6 using namespace std;
 7 
 8 const int N = 5,maxn = 25;
 9 
10 int n,cnt,Min;
11 int table[N],skip[maxn];
12 
13 bool Judge(int *num,int step){
14     for(int i = 0;i < N;i++){
15         if((num[i]>>step)&table[i]) return false;
16     }
17     return true;
18 }
19 
20 void init(){
21     memset(table,0,sizeof(table));
22     char str[maxn];
23     cnt = 0,Min = n*10;
24 
25     for(int i = 0;i < N;i++){
26         scanf("%s",str);
27         for(int j = 0;j < n;j++){
28             if(str[j] == ‘X‘) table[i] |= (1<<j);
29         }
30     }
31 
32     for(int i = 0;i <= n;i++){
33         if(Judge(table,i)) skip[cnt++] = i; 
34     }
35 }
36 
37 void dfs(int *s,int d,int time){
38     if(d == 10){
39         Min = min(Min,time);
40         return;
41     }
42 
43     if(time+skip[0]*(10-d) > Min) return;
44 
45     for(int i = 0;i < cnt;i++){
46         if(Judge(s,skip[i])){
47             int tmp[N];
48             for(int j = 0;j < N;j++){
49                 tmp[j] = ((s[j]>>skip[i]) | table[j]);
50             }
51             dfs(tmp,d+1,time+skip[i]);
52         }
53     }
54 }
55 
56 int main()
57 {
58 #ifdef GEH
59     freopen("input.txt","r",stdin);
60 #endif
61     while(~scanf("%d",&n) && n){
62         init();
63         dfs(table,1,n);
64         printf("%d\n",Min);
65     }
66     return 0;
67 }