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
