PROGRAM Main

  USE Data_Structures
  USE Algorithms

  IMPLICIT NONE

  CHARACTER(LEN=*), PARAMETER :: i_fmt = "(I1)"
  CHARACTER(LEN=*), PARAMETER :: r_fmt = "(F4.1)"

  TYPE(Graph) :: g
  CHARACTER(LEN=256) :: fname
  INTEGER :: source, destination
  REAL :: weight
  TYPE(List) :: path
  TYPE(Node), POINTER :: p

  WRITE(*, *)
  WRITE(*, "(A)") "Legrövidebb út számítása Bellman-Ford algoritmussal."
  WRITE(*, "(A)") "----------------------------------------------------"
  WRITE(*, *)
  WRITE(*, "(A)", ADVANCE="NO") "A gráfot tartalmazó fájl elérési útja: "
  READ(*, *) fname
  WRITE(*, *)

  g = From_File(fname)

  WRITE(*, "(A)") "A gráf éleinek halmaza (kezdőpont, végpont, súly):"
  CALL Print_Set(g%edges, i_fmt, r_fmt)
  WRITE(*, *)

  WRITE(*, "(A)", ADVANCE="NO") "A keresett út kezdőpontja: "
  READ(*, *) source
  WRITE(*, *)

  WRITE(*, "(A)", ADVANCE="NO") "A keresett út végpontja: "
  READ(*, *) destination
  WRITE(*, *)

  path = Bellman_Ford(g, source, destination)

  WRITE(*, "(A)") "A legrövidebb utat alkotó élek:"
  CALL Print_List(path, i_fmt, r_fmt)
  WRITE(*, *)

  WRITE(*, "(A)") "A legrövidebb út:"
  WRITE(*, i_fmt, ADVANCE="NO") source

  p => path%first
  weight = 0
  DO WHILE (ASSOCIATED(p))
    WRITE(*, "(A)", ADVANCE="NO") " -> "
    WRITE(*, i_fmt, ADVANCE="NO") p%data%destination
    weight = weight + p%data%weight
    p => p%next
  END DO
  WRITE(*, *)
  WRITE(*, *)

  WRITE(*, "(A)") "A legrövidebb út összsúlya:"
  WRITE(*, r_fmt) weight

END PROGRAM Main