Задание 24. Информатика. ЕГЭ. Поляков-8127

Python

from re import finditer

s = open('8120.txt').readline().strip()
nums = []
f = [5, -1, -5, 1] # остатки деления степеней восьмерки на 13
ml = 0

for g in finditer(r'[1-7][0-7]+', s):
    if len(g.group(0)) < ml:
        continue
    ts = g.group(0)
    len_ts = len(ts)
    pref = [0] * len_ts
    r = (4 - len_ts % 4) % 4
    pref[0] = f[r] * int(ts[0], 8) % 13
    for i in range(1, len_ts):
        pref[i] = (pref[i-1] + f[(r + i) % 4] * int(ts[i], 8)) % 13
    if pref[-1] == 0:
        nums.append(ts)
        ml = len_ts
    else:
        s_tmp = set()
        for k in range(len_ts - ml):
            if ts[k] not in s_tmp:
                s_tmp.add(ts[k])
                for p in range(len_ts - 1, ml + k, -1):
                    if pref[p] == pref[k]:
                        ml = max(ml, p - k)
                        nums.append(ts[k+1:p+1])
                        break
m = max(len(d) for d in nums)
nums = sorted([d for d in nums if len(d) == m])
print(s.find(nums[0]))

Ответ: \(605381\)