题解 | 动态字符串
动态字符串
https://www.nowcoder.com/practice/e2c51a6f126b41f9be403376c7adea15
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String str = scanner.next();
StringBuilder sen=new StringBuilder(str);
for(int i=sen.length()-3;i>=0;)
{
sen.insert(i,',');
i=i-3;
}
System.out.print(sen);
}
}