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ValidateIPAddress.swift
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ValidateIPAddress.swift
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/**
* Question Link: https://leetcode.com/problems/validate-ip-address/
* Primary idea: Determine whether they are iPv4 or iPv6, then handle them separately
*
* Time Complexity: O(n), Space Complexity: O(1)
*
*/
class ValidateIPAddress {
let IPv4 = "IPv4"
let IPv4Separator = Character(".")
let IPv6 = "IPv6"
let IPv6Separator = Character(":")
let InvalidIP = "Neither"
func validIPAddress(_ IP: String) -> String {
// detect IPv4 or IPv6
guard let isIPv4 = isPotentialIPv4(IP) else {
return InvalidIP
}
return isIPv4 ? isValidIPv4(IP) : isValidIPv6(IP)
}
private func isPotentialIPv4(_ IP: String) -> Bool? {
let isIPv4 = IP.contains(IPv4Separator), isIPv6 = IP.contains(IPv6Separator)
if isIPv4 || isIPv6 {
return isIPv4
} else {
return nil
}
}
private func isValidIPv4(_ IP: String) -> String {
if IP.contains("\(IPv4Separator)\(IPv4Separator)") || IP.first == IPv4Separator || IP.last == IPv4Separator {
return InvalidIP
}
let numbers = IP.split(separator: IPv4Separator)
guard numbers.count == 4 else {
return InvalidIP
}
for number in numbers {
guard let num = Int(number) else {
return InvalidIP
}
guard let first = number.first, first.isNumber else {
return InvalidIP
}
if first == "0", number.count > 1 {
return InvalidIP
}
if num < 0 || num > 255 {
return InvalidIP
}
}
return IPv4
}
private func isValidIPv6(_ IP: String) -> String {
if IP.contains("\(IPv6Separator)\(IPv6Separator)") || IP.first == IPv6Separator || IP.last == IPv6Separator {
return InvalidIP
}
let numbers = IP.split(separator: IPv6Separator)
guard numbers.count == 8 else {
return InvalidIP
}
for number in numbers {
let number = number.lowercased()
if number.count > 4 {
return InvalidIP
}
for char in number {
if !char.isHexDigit {
return InvalidIP
}
}
}
return IPv6
}
}