12 задание ЕГЭ по информатике

def found( s, substr ):
    return s.count( substr )
#==============================================================================
def substitute(s, old, new):
    return s.replace(old, new, 1)
#==============================================================================
def editor(s):
    while found(s, 'XXX') or found(s, 'ZYX') or found(s, 'ZXX'):
        s = substitute(s, 'XXX', 'ZZ')
        s = substitute(s, 'ZYX', 'X')
        s = substitute(s, 'ZXX', 'Y')
    return s
#==============================================================================
s = 'X' * 107
print( editor(s) )

"""
s = 'x'*int(1e7)
while 'xxx' in s or 'zyx' in s or 'zxx' in s:
    s = s.replace('xxx', 'zz', 1)
    
    # пока есть 'xxx', оператор не выполняется
    s = s.replace('zyx', 'x', 1)
 
    s = s.replace('zxx', 'y', 1)
 
print(s.count('zy'))
"""
# код можно заменить на:
n = int(1e7)
s = 'x'*nu
s = s.replace('xxxxx', 'zy')
 
while 'xxx' in s or 'zyx' in s or 'zxx' in s:
    s = s.replace('xxx', 'zz', 1)
    s = s.replace('zyx', 'x', 1)
    s = s.replace('zxx', 'y', 1)
 
print(s == 'zy'*(n//5))

st = 'X' * 107
while ('XXX' in st) or ('ZYX' in st) or ('ZXX' in st):
    st = st.replace('XXX', 'ZZ', 1)
    st = st.replace('ZYX', 'X', 1)
    st = st.replace('ZXX', 'Y', 1)
print(st)

s = 'x'*n