8.14 - hard - 45

233. Number of Digit One

精力已经耗尽。。。直接参考的这里的答案https://discuss.leetcode.com/topic/27565/java-python-one-pass-solution-easy-to-understand

class Solution(object):
    def countDigitOne(self, n):
        """
        :type n: int
        :rtype: int
        """
        if n <= 0:
            return 0
        q, x, ans = n, 1, 0
        while q > 0:
            digit = q % 10
            q /= 10
            ans += q * x
            if digit == 1:
                ans += n % x + 1
            elif digit > 1:
                ans += x
            x *= 10
        return ans