Codeforces Round #321 (Div. 2) D. Kefa and Dishes (状压dp,再A一发)

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 #include<queue>
 6 #include<vector>
 7 using namespace std;
 8 typedef long long ll;
 9 
10 /*
11     n,m,r
12 */
13 ll n,m,r,safy[20],dp[1<<18][20],rule[20][20];
14 int main(){
15     
16     while(scanf("%d%d%d",&n,&m,&r) != EOF){
17         memset(rule,0,sizeof(0));
18         memset(dp,-1,sizeof(dp));
19         for(int i = 0 ; i < n ; i ++) scanf("%d",&safy[i]);
20         for(int i = 0 ; i < r ; i ++){
21             int u,v,s;
22             scanf("%d%d%d",&u,&v,&s);
23             u-- ; v --;  rule[u][v] = s;
24         }
25     
26         for(int i = 0 ; i < n ; i ++){
27             dp[1<<i][i] = safy[i];
28         }
29         ll ans = 0;
30         for(int i = 0 ; i < (1<<n) ; i ++){        //*** *** 遍历每种状态 
31             
32             ll tmp = i;
33             ll cnt = 0;
34             while(tmp){
35                 if(tmp & 1) cnt ++;
36                 tmp >>= 1ll;
37             }
38             bool can = false;
39             if(cnt == m) can = true;
40             
41             for(int j = 0 ; j < n ; j ++){        //*******遍历最后吃过的 j
42              
43                 if(dp[i][j] == -1)     continue;        //还没有出现这种情况 
44                 if(can) ans = max(ans,dp[i][j]);    // 满足条件,更新答案 
45                 for(int k = 0 ; k < n ; k ++){    //******吃第k个 
46                     if(i & (1 << k )) continue;        //k已经吃过了 
47                     dp[i|(1 << k)][k] = max(dp[i][j] + rule[j][k] + safy[k],dp[i|(1 << k)][k]);
48                 }
49             }
50         }    
51         printf("%I64d\n",ans);
52     }    
53     return 0;
54 }