状压DP。。。在TSP的问题中把2进制状压改成3进制就行了。。。
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 100005
#define maxm 200005
#define eps 1e-10
#define mod 10000007
#define INF 1e17
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
typedef long long LL;
//typedef int LL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head
int h[maxn], next[maxm], v[maxm], cost[maxm];
int dp[maxn][11], hash[maxn];
int cnt, n, m;
const int inf = 0x3f;
const int tt = 1061109567;
void addedges(int a, int b, int c)
{
next[cnt] = h[a], h[a] = cnt, v[cnt] = b, cost[cnt] = c, cnt++;
}
void init(void)
{
cnt = 0;
memset(h, -1, sizeof h);
hash[1] = 1;
for(int i = 2; i <= 11; i++) hash[i] = hash[i-1] * 3;
}
void read(void)
{
int a, b, c;
while(m--) {
scanf("%d%d%d", &a, &b, &c);
addedges(a, b, c);
addedges(b, a, c);
}
}
bool check(int a, int b)
{
while(b--) a /= 3;
a %= 3;
return a;
}
void work(void)
{
int t = 59049;
for(int i = 0; i < t; i++)
for(int j = 0; j <= n; j++)
dp[i][j] = tt;
for(int i = 1; i <= n; i++) dp[hash[i]][i] = 0;
for(int i = 0; i < t; i++) {
for(int j = 1; j <= n; j++) {
if(dp[i][j] == tt) continue;
for(int e = h[j]; ~e; e = next[e]) {
int tmp = i % (hash[v[e] + 1]);
if(tmp >= 2 * hash[v[e]]) continue;
dp[i + hash[v[e]]][v[e]] = min(dp[i + hash[v[e]]][v[e]], dp[i][j] + cost[e]);
}
}
}
int ans = tt;
for(int i = 0; i < t; i++) {
int ok = 0;
for(int j = 1; j <= n; j++) {
int tmp = i % hash[j+1];
if(tmp < hash[j]) {
ok = 1;
break;
}
}
if(ok) continue;
for(int j = 1; j <= n; j++) ans = min(ans, dp[i][j]);
}
if(ans == tt) printf("-1\n");
else printf("%d\n", ans);
}
int main(void)
{
while(scanf("%d%d", &n, &m)!=EOF) {
init();
read();
work();
}
return 0;
}
