468. verifying the IP address

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468. verification IP Address

subject

Given a string  queryIP. If it works IPv4 Address , return "IPv4" ; If it works IPv6 Address , return "IPv6" ; If not of the above type IP Address , return "Neither" .

Effective IPv4 Address yes “x1.x2.x3.x4” Formal IP Address . among  0 <= xi <= 255  And  xi  Can not contain Leading zero . for example : “192.168.1.1” 、 “192.168.1.0” To be effective IPv4 Address , “192.168.01.1” Is invalid IPv4 Address ; “192.168.1.00” 、 “[email protected]” Is invalid IPv4 Address .

A valid IPv6 Address   Is a format of “x1:x2:x3:x4:x5:x6:x7:x8” Of IP Address , among :
1 <= xi.length <= 4
xi  It's a Hexadecimal string , It can contain numbers 、 Small letters ( 'a' To 'f' ) And capital letters ( 'A' To 'F' ).
stay  xi  Leading zeros are allowed in .
for example "2001:0db8:85a3:0000:0000:8a2e:0370:7334" and "2001:db8:85a3:0:0:8A2E:0370:7334" It works IPv6 Address , and "2001:0db8:85a3::8A2E:037j:7334" and "02001:0db8:85a3:0000:0000:8a2e:0370:7334" It's invalid IPv6 Address .

Example

Example 1：
Input ：queryIP = "172.16.254.1"
Output ："IPv4"
explain ： Effective IPv4 Address , return "IPv4"

Example 2：
Input ：queryIP = "2001:0db8:85a3:0:0:8A2E:0370:7334"
Output ："IPv6"
explain ： Effective IPv6 Address , return "IPv6"

Example 3：
Input ：queryIP = "256.256.256.256"
Output ："Neither"
explain ： neither IPv4 Address , Not yet IPv6 Address

explain

queryIP  Only by English letters , Numbers , character  '.'  and  ':'  form .

Ideas

The idea of the topic itself is not difficult , Is to process strings , But it's complicated , Extra care is needed . Here are a few things to pay attention to ：

1. about IPv4 Cannot contain a preamble 0 The problem of , image 192.0.0.1 Like this 0 It can exist .

2. For a correct IPv4, At last, there was an extra . Or a right one IPv6 There is one more on the last side : The situation of

C++ Code

class Solution {
public:
    bool checkIPv4(string s){
        int index=0, N=0;
        while(index<s.size())
        {
            string temp=""; // Create a new empty string to store each number 
            if( !('0'<=s[index] && s[index]<='9')) return false; // Encounter non number   return false
            else if (s[index]=='0' && !(index==s.size()-1 || s[index+1]=='.')) return false; // When the number is 0, And the back is not . Or not the last character 
            else // Encountered the first number 
            {
                temp+=s[index];// First, add the first number to the string 
                index++; // Then judge the next character 
                while(index<s.size() && '0'<=s[index] && s[index]<='9') // If it's a number 
                {
                    temp+=s[index]; index++;
                }
                if(index!=s.size() && s[index]!='.') return false; // It is not a legal character or . false
                N++; // Number of segments ++
                int num=stoi(temp); // Convert the previous string to a number 
                if(num<0 || num>255) return false;
                if(N==4 && s[index]=='.') return false;
            }
            index++;
        }
        return N==4; // Finally, judge whether it is 4 paragraph 
    }
    bool checkIPv6(string s){
        int index=0, N=0;
        while(index<s.size())
        {
            string temp=""; // Create a new empty string to store each number 
            if(! ( ('0'<=s[index] && s[index]<='9') || ('a'<=s[index] && s[index]<='f') || ('A'<=s[index] && s[index]<='F')))  return false;// Is not a specified legal character 
            else
            {
                temp+=s[index];// First, add the first number to the string 
                index++; // Then judge the next character 
                while(('0'<=s[index] && s[index]<='9') || ('a'<=s[index] && s[index]<='f') || ('A'<=s[index] && s[index]<='F')) // If it is a legal character 
                {
                    temp+=s[index]; index++;
                }
                if(index!=s.size() && s[index]!=':') return false; // It is not a legal character or : false
                N++;
                if(!(temp.size()>=1 && temp.size()<=4)) return false;
                if(N==8 && s[index]==':') return false; // Prevent a correct IPv6 There is an extra after the address :
            }
            index++;
        }
        return N==8;
    }
    string validIPAddress(string queryIP) {
        if(queryIP.size()<7 || queryIP.size()>39) return "Neither";
        if(checkIPv4(queryIP)==true) return "IPv4";
        if(checkIPv6(queryIP)==true) return "IPv6";
        return "Neither";
    }
};