Social Constraints

#include<iostream>
#include<algorithm>

using namespace std;

int a[22],b[22],c[22],index[22];

int p[] = {0,1,2,3,4,5,6,7};

int main()
{
    int n,m,i,tot,diff;

    while(scanf("%d%d",&n,&m)==2)
    {
        if(n==0 && m==0)
        {
            break;
        }

        tot = 0;

        for(i=1;i<=m;i++)
        {
            scanf("%d%d%d",&a[i],&b[i],&c[i]);
        }

        do
        {
            for(i=0;i<n;i++)
            {
                index[p[i]] = i;
            }

            int ok = 1;

            for(i=1;i<=m;i++)
            {
                diff = abs(index[a[i]]-index[b[i]]);

                if(c[i]>0)
                {
                    if(diff>c[i])
                    {
                        ok = 0;
                        break;
                    }
                }
                else
                {
                    if(diff<-c[i])
                    {
                        ok = 0;
                        break;
                    }
                }
            }

            tot+=ok;
        }

        while(next_permutation(p,p+n));

        printf("%d\n",tot);
    }

    return 0;
}