【DP】 HDOJ 3001 Travelling

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;
}