Code Golf: Finite-state machine!

Answer 1

Adam provided a reference implementation. I didn't see it before I made mine, but the logic is similar:

Edit: This is Python 2.6 code. I did not try to minimize length; I just tried to make it conceptually simple.

import sys
a = sys.stdin.read().split('\n')
states = a[0].split()
transitions = a[1:-2]
input = a[-2]
statelist = {}
for state in states:
    statelist[state] = {}

for start, char, end in [x.split() for x in transitions]:
    statelist[start][char] = end

state = states[0]
for char in input:
    if char not in statelist[state]:
        print state,char
        print "REJECT"
        exit()
    newstate = statelist[state][char]
    print state, char, '->', newstate
    state = newstate
if state[0].upper() == state[0]:
    print "ACCEPT"
else:
    print "REJECT"