题解 | 整数与IP地址间的转换

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.next();
        String str2 = in.next();
        String[] split = str.split("\\.");
        long result = 0;
        double power = 0;
        for(int i = 3;i>=0;i--){
            Integer num = Integer.valueOf(split[i]);
            result +=(long) (num*Math.pow(2,power));
            power +=8;
        }
        System.out.println(result);
        Long num2 = Long.valueOf(str2);
        String binaryString = Long.toBinaryString(num2);
        int len = binaryString.length();
        String str3 = "";
        for(int i =0;i<32-len;i++){
            str3+='0';
        }
        binaryString = str3+binaryString;
        int n = Integer.valueOf(binaryString.substring(0,8),2);
        int n2 = Integer.valueOf(binaryString.substring(8,16),2);
        int n3 = Integer.valueOf(binaryString.substring(16,24),2);
        int n4 = Integer.valueOf(binaryString.substring(24,32),2);
        StringBuilder sb = new StringBuilder();
        sb.append(n).append('.').append(n2).append('.').append(n3).append('.').append(n4);
        System.out.println(sb.toString());
    }
}