================ Part 1: the pickup network ================
|V| = 11 zones, |E| = 11 roads

BFS from the outlet in Keputih
  zone                hops  route
  Keputih             0     Keputih
  Gebang Putih        1     Keputih > Gebang Putih
  Klampis Ngasem      2     Keputih > Gebang Putih > Klampis Ngasem
  Semolowaru          3     Keputih > Gebang Putih > Klampis Ngasem > Semolowaru
  Sukolilo            1     Keputih > Sukolilo
  Medokan Semampir    2     Keputih > Sukolilo > Medokan Semampir
  Manyar Sabrangan    3     Keputih > Gebang Putih > Klampis Ngasem > Manyar Sabrangan
  Nginden Jangkungan  4     Keputih > Gebang Putih > Klampis Ngasem > Semolowaru > Nginden Jangkungan
  Mulyorejo           2     Keputih > Gebang Putih > Mulyorejo
  Kalijudan           3     Keputih > Gebang Putih > Mulyorejo > Kalijudan
  Dukuh Setro         -     unreachable by road

  edge slots scanned = 22, and 2|E| = 22
  furthest reachable zone: Nginden Jangkungan at 4 hops
  a 2-hop promise covers: Keputih, Gebang Putih, Klampis Ngasem, Sukolilo, Medokan Semampir, Mulyorejo, and nothing else

================ Part 2: the wash process ================
is a DAG: yes
one legal order of work:
  intake weigh invoice sort pretreat wash dry iron fold pack notify 

after adding 'notify -> invoice':
  is a DAG: no
  the cycle is: pack -> notify -> invoice -> pack
  no order of work can satisfy this
