题解 | 无限长正整数排列字符串

import java.util.Scanner;

// 求第n个字符
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        int n = in.nextInt();
        StringBuilder s = new StringBuilder();
        for(int i = 1;i<=n;i++){
            s.append(i);
        }
        // System.out.println(s.toString());
        System.out.println(s.charAt(n-1));
    }
}