Travelling HDU, travellinghdu

Travelling HDU, travellinghdu

Travel elling HDU-3001

Method: compress dp in a 3-digit state (a better way is to pre-process the y array corresponding to each State number and then use the fl table. The time complexity can be less than one n)

 1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 using namespace std; 5 typedef long long LL; 6 LL n,m,anss=0x3f3f3f3f3f3f3f3f; 7 LL y[20]; 8 LL dis[20][20]; 9 LL ans[100000][20];10 void split(LL x,LL y[])11 {12     for(LL i=1;i<=n;i++)13     {14         y[i]=x%3;15         x/=3;16     }17 }18 LL merge(LL y[])19 {20     LL ans=0,i,base=1;21     for(i=1;i<=n;i++)22         ans+=y[i]*base,base*=3;23     return ans;24 }25 int main()26 {27     LL i,j,kk,k,a,b,c,p;28     bool flag;29     while(scanf("%lld%lld",&n,&m)==2)30     {31         anss=0x3f3f3f3f3f3f3f3f;32         memset(dis,0x3f,sizeof(dis));33         memset(ans,0x3f,sizeof(ans));34         for(i=1;i<=m;i++)35         {36             scanf("%lld%lld%lld",&a,&b,&c);37             dis[a][b]=min(dis[a][b],c);38             dis[b][a]=min(dis[b][a],c);39         }40         for(i=0;i<=n;i++)41         {42             dis[0][i]=dis[i][0]=0;43             dis[i][i]=0;44         }45         for(i=1;i<=n;i++)46             y[i]=2;47         kk=merge(y);48         memset(ans[0],0,sizeof(ans[0]));49         for(i=1;i<=kk;i++)50         {51             flag=true;52             split(i,y);53             for(j=1;j<=n;j++)54                 if(y[j]>0)55                 {56                     y[j]--;57                     p=merge(y);58                     for(k=1;k<=n;k++)59                         ans[i][j]=min(ans[i][j],ans[p][k]+dis[k][j]);60                     y[j]++;61                 }62                 else63                     flag=false;64             if(flag)65                 anss=min(anss,*min_element(ans[i]+1,ans[i]+n+1));66         }67         if(anss!=0x3f3f3f3f3f3f3f3f)68             printf("%lld\n",anss);69         else70             printf("-1\n");71     }72     return 0;73 }

The following error was reported:

1.65 rows, two minutes into max

2. ans is not reset for each group of data (a waste of 2 hours)