A waste of processor cycles

import re

def nice_string(s):

    """ This is supposed to check if a string looks like English. All it
        does for the time being is return `False` if the string contains a
        space followed by punctuation, or punctuation followed by a letter.
        Returns `True` otherwise. """

    if re.search(' [\.\?,]',s):
        return False
    if re.search('[\.\?,]\w',s):
        return False
    return True



def solve1(ciphertext):

    """ Checks permutations of a string with different offsets between one
        character and the next. When a character is reached, it is replaced
        with an asterisk to indicate that it should be skipped next time. """

    nchars = len(ciphertext)
    for delta in range(1,nchars):
        c = ciphertext
        out = ""
        p = 0
        for i in range(nchars):
            while c[p]=="*":
                p = (p+nchars-1) % nchars
            out = out + c[p]
            c = c[:p] + "*" + c[p+1:]
            p = (p+delta) % nchars
        if nice_string(out):
            print "(solve1) delta=%3d: %s" % (delta, out[:72])
    if len(c) != len(ciphertext):
        raise hell



def solve2(ciphertext):

    """ Like `solve1()`, but with an offset that increments at each step. """

    nchars = len(ciphertext)
    for delta in range(1,nchars):
        c = ciphertext
        out = ""
        p = 0
        d = delta
        for i in range(nchars):
            while c[p]=="*":
                p = (p+1) % nchars
            out = out + c[p]
            c = c[:p] + "*" + c[p+1:]
            p = (p+d) % nchars
            d = d + 1
        if nice_string(out):
            print "(solve2) delta=%3d: %s" % (delta, out[:72])



def solve3(ciphertext):

    """ Like `solve1()`, but with offsets based on the digits of pi. """

    pi500 = '314159265358979323846264338327950288419716939937510582097494' \
            '459230781640628620899862803482534211706798214808651328230664' \
            '709384460955058223172535940812848111745028410270193852110555' \
            '964462294895493038196442881097566593344612847564823378678316' \
            '527120190914564856692346034861045432664821339360726024914127' \
            '372458700660631558817488152092096282925409171536436789259036' \
            '001133053054882046652138414695194151160943305727036575959195' \
            '309218611738193261179310511854807446237996274956735188575272' \
            '48912279381830119491'

    nchars = len(ciphertext)
    c = ciphertext
    out = ""
    p = 0
    for i in range(nchars):
        while c[p]=="*":
            p = (p+nchars-1) % nchars
        out = out + c[p]
        c = c[:p] + "*" + c[p+1:]
        d = int(pi500[i]) or 10
        p = (p+d) % nchars
    if nice_string(out):
        print "(solve3)",out[:72]



def tryall():

    """ Send every cyclical permutation to the `solve()` functions """

    cipher = "HA, TITEXGB   DTESTRI AT UE A ONTCTSOMNDEOTA DN UEYCN HRUSN.I" \
             "ETH AEPT CR  F TNGEYI?OI A RCA UODUTYE COHNTUI?EURYI HEPSA T R"

    """ No luck with this either:
    cipher = " ORIC.ELON TIHPE, E RET THELXLA.  E OWR IU IGEYLRLIA -AOEW NV" \
             " GEU YLARNO AHOTAX SCATIATXI LTT SNITTL STI LL. FSSOYKWE RWOI" \
             " ENHETUAI  ATLR EE SOF, NPSBARSCTEO R EO AIU YIECAULSNH: ITRS" \
             "  MERHASDYTSCE OFTK RA LIWSTOC ORD VLWEIDS OLSNI!NHU EIA AIS " \
             "T DE TKDTE XIEOSAFWSMPIOT  RVONR MOIRTH ONIO NET SFLPI AUDFND" \
             "MA ZZOI"
    """

    for i in range(len(cipher)):
        solve1(cipher)
        solve2(cipher)
        solve3(cipher)
        cipher = cipher[-1] + cipher[:-1]  # Rotate string



tryall()