Necklace
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 327680/327680 K (Java/Others)
Total Submission(s): 522 Accepted Submission(s): 168
Problem Description
One day , Partychen gets several beads , he wants to make these beads a necklace . But not every beads can link to each other, every bead should link to some particular bead(s). Now , Partychen wants to know how many kinds of necklace he can make.
Input
It consists of multi-case .
Every case start with two integers N,M ( 1<=N<=18,M<=N*N )
The followed M lines contains two integers a,b ( 1<=a,b<=N ) which means the ath bead and the bth bead are able to be linked.
Every case start with two integers N,M ( 1<=N<=18,M<=N*N )
The followed M lines contains two integers a,b ( 1<=a,b<=N ) which means the ath bead and the bth bead are able to be linked.
Output
An integer , which means the number of kinds that the necklace could be.
Sample Input
3 3
1 2
1 3
2 3
Sample Output
2
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<vector>
using namespace std; int n,m;
vector <int> a[];
long long dp[(<<)+][];
void make_ini()
{
int i,j;
int s,r,u;
memset(dp,,sizeof(dp));
dp[][]=;
for(i=;i<(<<n);i++)
{
for(j=;j<n;j++)
{
if(dp[i][j]==)continue;
for(s=;s<a[j].size();s++)
{
u=a[j][s];
if( (i&(<<u))> ) continue;
r=( i | (<<u) );
dp[r][u]+=dp[i][j];
}
}
}
long long Sum=;
for(i=;i<a[].size();i++)
Sum+=dp[(<<n)-][a[][i]];
printf("%I64d\n",Sum);
}
int main()
{
int i,x,y;
while(scanf("%d%d",&n,&m)>)
{
for(i=;i<n;i++)
{
a[i].clear();
}
for(i=;i<=m;i++)
{
scanf("%d%d",&x,&y);
x--;
y--;
a[x].push_back(y);
a[y].push_back(x);
}
make_ini();
}
return ;
}