longclaps

def euler14(limit):
    cache, kolNums = {1: 1}, []
    for n in range(2, limit):
        while n not in cache:
            kolNums.append(n)
            n = 3 * n + 1 if n % 2 else n // 2
        res = cache[n]
        while kolNums:
            res += 1
            cache[kolNums.pop()] = res
    print(*max(cache.items(), key=lambda e: e[1]))

#!/usr/bin/python3
import re

ptrn = re.compile(r'^\s*user_pref\(([^\)]+)\);').search
unic = set()
with open("user.js", "r") as fi, open("user_nodup.js", "w") as fo:
    for s in fi:
        m = ptrn(s)
        if m:
            data = m.group(0)
            if data in unic:
                print(s, end="")  # duplicate
                continue
            unic.add(data)
        fo.write(s)

from itertools import product

for e in product([1, 2, 3], repeat=2):
    print(e)

SELECT
  item_id,
  COUNT(*) AS cnt
FROM (SELECT DISTINCT *
      FROM item_user) AS T
GROUP BY item_id;

SELECT
  item_id,
  COUNT(DISTINCT user_id) AS cnt
FROM item_user
GROUP BY item_id;

import re

d = {"a b c": "x", "a b": "y", "a": "z"}
data = "a b c a b a a a b c"
print(re.sub(r'a( b( c)?)?', lambda m: d[m.group()], data))
print(re.sub(r'a b c|a b|a', lambda m: d[m.group()], data)) # можно и так