题解 | #合法IP#

活用正则表达式

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] fields = scanner.nextLine().split("\\.");
        if (fields.length != 4) {
            System.out.println("NO");
            return;
        }
        for (String field : fields) {
            if (!field.matches("[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]")) {
                System.out.println("NO");
                return;
            }
        }
        System.out.println("YES");
    }
}