Lecture Notes 18 Oct 2017

def main():
  # open input file
  in_file = open ("./input.txt", "r")

  # open output file
  out_file = open ("./output.txt", "w")

  # read line by line and write out
  for line in in_file:
    out_file.write (line)

  print ("Output file is written.")

  # close the files
  in_file.close()
  out_file.close()

main()

def main ():
  # open file for reading
  in_file = open ("./dna.txt", "r")

  # read the number of pairs
  num_pairs = in_file.readline ()
  num_pairs = num_pairs.strip()
  num_pairs = int (num_pairs)

  # read each pair of dna strands
  for i in range (num_pairs):
    st1 = in_file.readline()
    st2 = in_file.readline()

    st1 = st1.strip()
    st2 = st2.strip()

    st1 = st1.upper ()
    st2 = st2.upper ()

    # order the strands by size
    if (len(st1) > len (st2)):
      dna1 = st1
      dna2 = st2
    else:
      dna1 = st2
      dna2 = st1

    # get all substrands of dna2
    wnd = len (dna2)
    while (wnd > 1):
      start_idx = 0
      while ((start_idx + wnd) <= len(dna2)):
        sub_strand = dna2[start_idx: start_idx + wnd]
        print (sub_strand)
        # move the window by one
        start_idx += 1
      # decrease the window size
      wnd = wnd - 1

  # close the file
  in_file.close()

main()