P079.py

# -*- coding: utf-8 -*-

#==============================================================================
# A common security method used for online banking is to ask
# the user for three random characters from a passcode. For
# example, if the passcode was 531278, they may ask for the
# 2nd, 3rd, and 5th characters; the expected reply would
# be:317.
#
# The text file, keylog.txt, contains fifty successful login
# attempts.
#
# Given that the three characters are always asked for in
# order, analyse the file so as to determine the shortest
# possible secret passcode of unknown length.
#==============================================================================

# Was determined manually by looking at the key.
# It was determined by finding which number appeared before another one.
print 73162890