public int LargestComponentSize(int[] A)
{
int n = A.Max();
var uf = new UF(n + 1);
foreach (var a in A)
{
int t = (int)Math.Sqrt(a);
for (int k = 2; k <= t; k++)
{
if (a % k == 0)
{
uf.Union(a, k);
uf.Union(a, a / k);
}
}
}
var m = new Dictionary <int, int>();
int res = 1; // with itself, min = 1;
foreach (var a in A)
{
int x = uf.FindRoot(a);
if (!m.ContainsKey(x))
{
m.Add(x, 0);
}
res = Math.Max(res, ++m[x]);
}
return(res);
}