POJ-2288 状压dp Hamilton回路

题意:Hamilton回路的权值为:

1、经过的每条边的两个点的点权和

2、连续经过两点的乘积

3、如果三条边形成三角形则再加上三个点权的乘积

求最大值+路径条数

思路:10来个点用一个小的邻接矩阵就可以判断是否相连,判断三角形就可以在dp加一维记录前两个点的信息,枚举的时候多枚举到前2个点

即dp[state][pre][now],表示当前为state、前一个点pre、当前点now的最大权值,路径条数跟最短路条数的记录方法一样

错的地方:没判断dp[state][pre][now] == -1就WA了,加上就A了,我之前明明都加上了i & (1<<j)这类点与状态冲突的判断,原因我猜是初始化+刷表法,-1是不合法不存在的状态,没加上会导致后面别的状态被刷了

代码:

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 #include <queue>
 6 #include <vector>
 7 #define LL long long
 8 #define INF 0x3f3f3f3f
 9 #define debug(x) cout << #x << " = " << x << endl
10 using namespace std;
11 
12 LL dp[1<<13][14][14], num[1<<13][14][14];
13 LL a[14];
14 bool d[14][14];
15 
16 int main() {
17     int t, n, m;
18     scanf("%d", &t);
19     while (t--){
20         scanf("%d%d", &n, &m);
21         memset(d, 0, sizeof d);
22         for (int i = 0; i < n; i++) scanf("%lld", &a[i]);
23         for (int i = 0; i < m; i++){
24             int u, v;
25             scanf("%d%d", &u, &v);
26             u--, v--;
27             d[u][v] = d[v][u] = 1;
28         }
29         if (n == 1){
30             printf("%lld 1
", a[0]);
31             continue;
32         }
33         memset(dp, -1, sizeof dp);
34         memset(num, 0, sizeof num);
35         for (int i = 0; i < n; i++){
36             for (int j = 0; j < n; j++){
37                 if (!d[i][j]) continue;
38                 if (i == j) continue;
39                 dp[(1<<i)+(1<<j)][i][j] = a[i]+a[j]+a[i]*a[j];
40                 num[(1<<i)+(1<<j)][i][j] = 1;
41             }
42         }
43         //dp[state][pre][now]
44         for (int i = 3; i < (1<<n); i++){
45             for (int j = 0; j < n; j++){
46                 if (!(i & (1 << j))) continue;
47                 for (int k = 0; k < n; k++){
48                     if (!(i & (1 << k))) continue;
49                     if (!d[j][k]) continue;
50                     if (dp[i][j][k] == -1) continue;
51                     for (int r = 0; r < n; r++){
52                         if (i & (1 << r)) continue;
53                         if (!d[k][r]) continue;
54                         LL tmp = dp[i][j][k] + a[r] + a[k]*a[r];
55                         if (d[j][r]) tmp += a[j]*a[k]*a[r];
56                         int nxt = i + (1 << r);
57                         if (tmp > dp[nxt][k][r]){
58                             dp[nxt][k][r] = tmp;
59                             num[nxt][k][r] = num[i][j][k];
60                         }
61                         else if (tmp == dp[nxt][k][r])
62                             num[nxt][k][r] += num[i][j][k];
63                     }
64                 }
65             }
66         }
67         LL ans = -1, sum = 0;
68         for (int i = 0; i < n; i++){
69             for (int j = 0; j < n; j++){
70                 if (i == j) continue;
71                 if (!d[i][j]) continue;
72                 if (dp[(1<<n)-1][i][j] > ans){
73                     ans = dp[(1<<n)-1][i][j];
74                     sum = num[(1<<n)-1][i][j];
75                 }
76                 else if (ans == dp[(1<<n)-1][i][j])
77                     sum += num[(1<<n)-1][i][j];
78             }
79         }
80         if (ans == -1) printf("0 0
");
81         else printf("%lld %lld
", ans, sum/2);
82     }
83     return 0;
84 }
原文地址:https://www.cnblogs.com/QAQorz/p/10186879.html