you can have some vector registers n_acc, ns, idx_acc, idxs, then you can do

  // (initialize ns and idxs by reading from the array
  //  and adding the apropriate constant to the old value of idxs.)
  n_acc = min(n_acc, ns);
  const is_new_min = eq(n_acc, ns);
  idx_acc = blend(idx_acc, idxs, is_new_min);

you can consult the list of toys here: https://www.intel.com/content/www/us/en/docs/intrinsics-guid...