[codewars] - int32 to IPv4 二进制十进制 ip地址转换

原题 https://www.codewars.com/kata/int32-to-ipv4/train/java

Take the following IPv4 address: 128.32.10.1

This address has 4 octets where each octet is a single byte (or 8 bits).

1st octet 128 has the binary representation: 10000000

2nd octet 32 has the binary representation: 00100000

3rd octet 10 has the binary representation: 00001010

4th octet 1 has the binary representation: 00000001

So 128.32.10.1 == 10000000.00100000.00001010.00000001

Because the above IP address has 32 bits, we can represent it as the unsigned 32 bit number: 2149583361

Complete the function that takes an unsigned 32 bit number and returns a string representation of its IPv4 address.

Examples

2149583361 ==> "128.32.10.1" 32 ==> "0.0.0.32" 0 ==> "0.0.0.0"