题解 | #整数与IP地址间的转换#

import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
            String IP=sc.nextLine();
            Long num=sc.nextLong();
            System.out.println(ipToNum(IP));
            System.out.println(NumToIp(num));
            
            
        
    }
    static long ipToNum(String IP){//将ip转换为整数（必须是Long，int溢出），赋值时要加L，不然是int
        String[] str=IP.split("\\.");
        long ans=0L;
        for(String s:str){
            long n=Long.parseLong(s);
            if(n>255||n<0) return -1;
            ans=ans<<8;
            ans+=n;

        }
        return  ans;
    }
    
    static String NumToIp(long num){
         Deque<String> queue=new LinkedList<>();
        while(num!=0){
            int m=(int)(num%256);
            num=num>>>8;
            queue.addFirst(String.valueOf(m));
            queue.addFirst(".");
        }
        queue.removeFirst();
        String ans="";
        for(String s:queue){
            ans+=s;
        }
        return ans;
    }
}