400. Nth Digit

Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...

Note:
n is positive and will fit within the range of a 32-bit signed integer (n < 231).

Example 1:

Input:
3

Output:
3

Example 2:

Input:
11

Output:
0

Explanation:
The 11th digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... is a 0, which is part of the number 10.

class Solution:
    def findNthDigit(self, n):
        """
        :type n: int
        :rtype: int
        """
        pos = 0
        while True:
            temp = 9*(10**pos)*(pos + 1)
            if temp>=n:
                break
            n -= temp
            pos += 1
        a,b = divmod(n,pos+1)
        if b==0:
            a -= 1
            b = pos+1
        return int(str(10**(pos) + a)[b-1])

先找到位于哪个区间（1-9,10-99,100-999...），然后确定是这个区间的那一个数，然后确定是哪一位的数字。
话说写的有点麻烦，有点嫌弃自己这个代码。。