HDU 3001 Travelling

#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <stack>
#include <map>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <utility>
using namespace std;

#define rep(i,j,k) for (int i=j;i<=k;i++)
#define Rrep(i,j,k) for (int i=j;i>=k;i--)

#define Clean(x,y) memset(x,y,sizeof(x))
#define LL long long
#define ULL unsigned long long
#define inf 0x7fffffff
#define mod %100000007

#define mp make_pair
#define fi first
#define se second

#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define mid int m=(l+r)>>1

int n,m;
int a[12][12];
int state[60000][11]; //存每一个状态的三进制下每一位的值。
int Tree_Pow[12];
int dp[60000][11];

void init()
{
Tree_Pow[0] = 1;
rep(i,1,10) Tree_Pow[i] = 3 * Tree_Pow[i-1];
rep(i,1,Tree_Pow[10])
{
int temp = i;
Rrep(j,10,1)
{
while( temp >= Tree_Pow[j-1] )
{
temp -= Tree_Pow[j-1];
state[i][j]++;
}
}
}
}

int main()
{
init();
while( ~scanf("%d%d",&n,&m) )
{
Clean(a,0);
int ta,tb,tc;
int ans = inf;
rep(i,1,m)
{
scanf("%d%d%d",&ta,&tb,&tc);
if ( !a[ta][tb] )
{
a[ta][tb] = tc;
a[tb][ta] = tc;
}
else
{
a[ta][tb] = min(a[ta][tb] , tc);
a[tb][ta] = min(a[tb][ta] , tc);
}
}
int uplim = Tree_Pow
;
Clean(dp,-1);
rep(i,1,uplim-1)
{
rep(j,1,n)
if ( state[i][j] )
{
int last = i - Tree_Pow[j - 1];//得到上一个状态
if ( last == 0 )
{
if ( state[i][j] == 1 )
{
dp[i][j] = 0;
}
}
else
{
rep(k,1,n) //枚举上一个城市
if ( k != j && state[last][k] && dp[last][k] != -1 && a[k][j] )
{
if ( dp[i][j] == -1 ) dp[i][j] = dp[last][k] + a[k][j];
else dp[i][j] = min( dp[i][j] , dp[last][k] + a[k][j] );
}
}
}
bool can = true;
rep(j,1,n) if ( state[i][j] == 0 ) can = false;
if ( can ) // 检查当前状态是否将所有的城市都遍历过了
rep(j,1,n) if (dp[i][j]!=-1) ans = min( ans , dp[i][j] );
}
if ( ans == inf ) puts("-1");
else cout<<ans<<endl;
}

return 0;
}