python--剑指offer--中等--43. 1～n整数中1出现的次数

class Solution: def countDigitOne(self, n: int) -> int: digit, res = 1, 0 high, cur, low = n // 10, n % 10, 0 while high != 0 or cur != 0: if cur == 0: res += high * digit elif cur == 1: res += high * digit + low + 1 else: res += (high + 1) * digit low += cur * digit cur = high % 10 high //= 10 digit *= 10 return res