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.
Approach:
This problem is actually quite brain-intensive; you first need to find the interval, and then find the position.
class Solution { public int findNthDigit(int n) { if(n<10) return n; long num = 9; int count = 1; while(n > count * num){ n -= num * count; count ++; num *= 10; } long res = num/9 + (n-1)/count; return Integer.parseInt(String.valueOf(res).substring((n-1)%count, (n-1)%count+1)); } } This siteOriginal articleAll follow "Attribution-NonCommercial-ShareAlike 4.0 License (CC BY-NC-SA 4.0)Please retain the following annotations when sharing or adapting:
Original author:Jake Tao,source:"400. Nth Digit"
