strange_calculator.py

from collections import deque
import math


def reverse_ends(n):
    log = int(math.log10(n))
    s = n // (10 ** log)
    e = n % 10
    n = n - e + s
    n = n + (e - s) * 10 ** log
    return n


def strange_calculator(n):
    queue = deque([(1, 1)])
    ans = None
    cache = set()

    while queue:
        tmp, tmp_route = queue.popleft()
        if tmp == n:
            ans = tmp_route
            break

        reversed = reverse_ends(tmp)
        if (reversed != tmp or reversed & (reversed - 1) != 0) and reversed not in cache:
            queue.append((reversed, (tmp_route << 1) | 0))
            cache.add(reversed)

        if tmp * 2 not in cache:
            queue.append((tmp * 2, (tmp_route << 1) | 1))
            cache.add(tmp * 2)
        print(queue[0])

    return ans