68. The second algorithm is simple and swift N digital

In the infinite sequence of integers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... found in the n-th digit.

Note:
n-and is a positive number in the range of 32 to the shaping (n <231).

Example 1:

Input:
3

Output:
3
Example 2:

Input:
11

Output:
0

Description:
The first 11 digits is 0 in the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ..., it is the part 10.

solution:
 

func findNthDigit(_ n: Int) -> Int {
        var n = n
        var carry = 1
        var bits = 1
        while n > carry * bits * 9 {
            n -= carry * 9 * bits
            carry += 1
            bits *= 10
        }
        
        let num = (n - 1)/carry + bits
        let mol = ((carry - n % carry) % carry) + 1
        
        var dev = 1
        
        for _ in 0..<mol-1 {
            dev *= 10
        }
        
        return ((num % (dev * 10)) / dev)
        

    }