_400.java

package com.fishercoder.solutions.firstthousand;

public class _400 {

    public static class Solution1 {
        /*
         * credit: https://discuss.leetcode.com/topic/59314/java-solution:
         * <p>
         * 1. find the length of the number where the nth digit is from 2. find the actual number where
         * the nth digit is from 3. find the nth digit and return
         */
        public int findNthDigit(int n) {
            int len = 1;
            long count = 9;
            int start = 1;

            while (n > len * count) {
                n -= len * count;
                len += 1;
                count *= 10;
                start *= 10;
            }

            start += (n - 1) / len;
            String s = Integer.toString(start);
            return Character.getNumericValue(s.charAt((n - 1) % len));
        }
    }
}