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400. Nth Digit

Math Binary Search

Problem - Nth Digit

Medium

Given an integer n, return the nth digit of the infinite integer sequence [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...].

 

Example 1:

Input: n = 3
Output: 3

Example 2:

Input: n = 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.

 

Constraints:

  • 1 <= n <= 231 - 1

Solutions

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class Solution:
    def findNthDigit(self, n: int) -> int:
        val, count = 1, 9
        while val * count < n:
            n -= val * count
            val += 1
            count *= 10

        num = 10 ** (val - 1) + ((n - 1) // val)
        index = (n - 1) % val
        return int(str(num)[index])

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 17.8 MB (39.35%)