leetcode/problems/src/math/NthDigit.java at master · KindleBooks66/leetcode · GitHub

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package math;

/** Created by gouthamvidyapradhan on 05/11/2019 */

public class NthDigit {

public static void main(String[] args) {

System.out.println(new NthDigit().findNthDigit(1000000000));

}

public int findNthDigit(int n) {

if (n >= 1 && n <= 9) return n;

long sum = 0L;

for (int i = 0; ; i++) {

long pow = (9 * (new Double(Math.pow(10, i)).longValue())) * (i + 1);

sum += pow;

if (sum >= n) {

long diff = (long) n - (sum - pow);

long num = diff / (i + 1);

long mod = diff % (i + 1);

long result = new Double(Math.pow(10, i)).intValue() + (num - 1) + (mod > 0 ? 1 : 0);

String resultStr = String.valueOf(result);

return (mod == 0)

? Integer.parseInt(String.valueOf(resultStr.charAt(resultStr.length() - 1)))

: Integer.parseInt(String.valueOf(resultStr.charAt((int) mod - 1)));

}

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