题目：

题解：

class Solution:
    def findNthDigit(self, n: int) -> int:
        d, count = 1, 9
        while n > d * count:
            n -= d * count
            d += 1
            count *= 10
        index = n - 1
        start = 10 ** (d - 1)
        num = start + index // d
        digitIndex = index % d
        return num // 10 ** (d - digitIndex - 1) % 10