leetcode_gym/_problems/nthdigit.md

layout, title, last_solved, category, leetcode_url, status

layout	title	last_solved	category	leetcode_url	status
page	nth digit		math	https://leetcode.com/problems/nth-digit/	Attempted

Problem

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.

Solution

Do not understand logic yet. Learn from this discussion

{% highlight python %}

def findNthDigit(self, n: int) -> int:
    
    # https://leetcode.com/problems/nth-digit/discuss/88369/0ms-C%2B%2B-Solution-with-Detail-Explanation
    
    # 1) find out how many digits the number has (n=250, digits=3)
    base=9
    digits=1
    while n-base*digits > 0:
        n-=base*digits
        base*=10
        digits+=1
        print(n, base, digits)
        
    # 2) calc what the number is
    index = (n-1) % digits
    offset = (n-1) / digits
    start = pow(10, digits-1)
    
    print(index, offset, start)
    return str(int(start+offset))[index]

{% endhighlight %}