UVa 10801 Lift Hopping / floyd

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std;
int a[110][110];
int b[110];
int n,m;

void floyd()
{
	int i,j,k;
	for(k = 0;k <= 100; k++)
			for(i = 0;i <= 100; i++)
				for(j = 0;j <= 100; j++)
						a[i][j] = min(a[i][j],a[i][k]+a[k][j]+60);

}
int main()
{
	int t,n,i,j,k;
	while(scanf("%d %d",&n,&m)!=EOF)
	{
		//for(k = 1;k <= n; k++)
		for(i = 0;i <= 100; i++)
			for(j = 0;j <= 100; j++)
			{
				if(i == j)
					a[i][j] = 0;
				else
					a[i][j] = 999999999;
			}
		for(i = 0; i < n; i++)
			scanf("%d",&b[i]);
		getchar();
		for(i = 0; i < n; i++)
		{
			char str[1000];
			char *p;
			gets(str);
			//puts(str);
			p = strtok(str," ");
			int cnt[110];
			int j = 0;
			while(p)
			{
				cnt[j++] = atoi(p);
				p = strtok(NULL," ");
			}
			for(k = 1 ;k < j; k++)
			{
				for(t = 0; t < k; t++)
				{
					a[cnt[t]][cnt[k]] = min(a[cnt[t]][cnt[k]],b[i]*abs(cnt[k]-cnt[t]));
					a[cnt[k]][cnt[t]] = min(a[cnt[k]][cnt[t]],b[i]*abs(cnt[k]-cnt[t]));
				}
			}
		}
		floyd();
		if(a[0][m] == 999999999)
			puts("IMPOSSIBLE");
		else
			printf("%d\n",a[0][m]);
	}
	return 0;
}