Wormholes （bellman）

求负环自然要用 belllman

#include <stdio.h>
#include <string.h>
int F,n,m,w,p,dist[501];
structnode
{
    int s,e,t;
}grid[5500];
int bellman()
{
    int i,k;
    memset (dist,0,sizeof (dist));
    for (k=1;k<=n-1;k++)
        for(i=1;i<=p;i++)
            if (dist[ grid[i].s ]> dist[ grid[i].e ]+grid[i].t)
            dist[ grid[i].s ]=dist[ grid[i].e ]+grid[i].t;
    for (i=1;i<=p;i++)
        if (dist[ grid[i].s ]> dist[ grid[i].e ]+grid[i].t)
        return 1;
    return 0;
}
int main()
{
    int s,e,t;
    scanf("%d",&F);
    while (F--)
    {
        p=1;
        memset(grid,0,sizeof(grid));
        scanf("%d%d%d",&n,&m,&w);
        while(m--)
        {
            scanf("%d%d%d",&s,&e,&t);
            grid[p].s=s;grid[p].e=e;grid[p++].t=t;
            grid[p].s=e;grid[p].e=s;grid[p++].t=t;

        }
        while(w--)
        {
            scanf("%d%d%d",&s,&e,&t);
            grid[p].s=s;grid[p].e=e;grid[p++].t=-t;
        }
        printf("%s\n",bellman()?"YES":"NO");
    }
	return 0;
}