Part 1 - cheapest shuttle network over 10 branches, 18 candidate links
  link                                 km    decision
  Gubeng      - Kertajaya        0.5    lay it
  Klampis     - Kertajaya        0.6    lay it
  Gebang      - Kertajaya        0.7    lay it
  Darmo       - Wonokromo        0.7    lay it
  Manyar      - Gubeng           0.8    lay it
  Gebang      - Klampis          0.9    skip (already reachable)
  Gubeng      - Ngagel           0.9    lay it
  Ngagel      - Darmo            1.0    lay it
  Manyar      - Ngagel           1.1    skip (already reachable)
  Keputih     - Gebang           1.2    lay it
  Ngagel      - Wonokromo        1.3    skip (already reachable)
  Klampis     - Manyar           1.4    skip (already reachable)
  Gebang      - Rungkut          1.5    lay it
  Darmo       - Gubeng           1.6    skip (already reachable)
  Keputih     - Rungkut          1.8    skip (already reachable)
  Keputih     - Kertajaya        2.0    skip (already reachable)
  Wonokromo   - Rungkut          2.2    skip (already reachable)
  Rungkut     - Kertajaya        2.5    skip (already reachable)
  links laid        : 9  (needed: 9)
  network length    : 7.9 km
  every link laid   : 22.7 km
  saved             : 14.8 km (65.2% of the candidate length)
  Prim's answer     : 7.9 km -- identical

Part 2 - a legal order for the 9 stages
  intake -> weigh -> sort -> price -> wash -> dry -> press -> fold -> handover
  earliest finish per stage:
    intake       4 min
    weigh        7 min
    sort        10 min
    price        9 min
    wash        45 min
    dry         85 min
    press       97 min
    fold       105 min
    handover   108 min
  longest chain (108 min): intake -> sort -> wash -> dry -> press -> fold -> handover
