【字符串】468. 验证IP地址

 1 class Solution {
 2 public:
 3     string validIPAddress(string IP) 
 4     {
 5         if (isValidIPv4(IP)) 
 6         {
 7             return "IPv4"; 
 8         }
 9         if (isValidIPv6(IP)) 
10         {
11             return "IPv6";
12         }
13         return "Neither";
14     }
15     
16     // 优雅的split
17     void split(const string s, vector<string>& vs, const char delim= ‘ ‘)
18     {
19         istringstream iss(s);
20         string temp;
21         while (getline(iss,temp,delim))
22         {
23             vs.emplace_back(move(temp));
24         }
25         if (!s.empty() && s.back() == delim) 
26         {
27             vs.push_back({});
28             //加这句的原因是getline不会识别最后一个delim,避免误判"172.16.254.1.","2001:0db8:85a3:0:0:8A2E:0370:7334:"之类的情况
29         }
30     }
31     
32     // 判定是否IPv4
33     bool isValidIPv4(string IP)
34     {
35         vector<string> vs;
36         split(IP,vs,‘.‘);
37         if (vs.size()!=4) 
38         {
39             return false;
40         }
41         
42         for (auto &v:vs) 
43         {
44             if (v.empty() || (v.size()>1 && v[0] == ‘0‘) || v.size()>3) 
45             {
46                 return false;
47             }
48             for (auto c:v) 
49             {
50                 if (!isdigit(c)) 
51                 {
52                     return false;
53                 }
54             }
55             int n = stoi(v);
56             if (n<0||n>255) 
57             {
58                 return false;
59             }
60         }
61         
62         return true;
63     }
64     
65     // 判定是否IPv6
66     bool isValidIPv6(string IP)
67     {
68         vector<string> vs;
69         split(IP,vs,‘:‘);
70         if (vs.size()!=8) 
71         {
72             return false;
73         }
74         for (auto &v:vs) 
75         {
76             if (v.empty() || v.size()>4 ) 
77             {
78                 return false;
79             }
80             for (auto c:v)
81             {
82                 if (!(isdigit(c) || (c>=‘a‘&&c<=‘f‘) || (c>=‘A‘&&c<=‘F‘))) 
83                 {
84                     return false;
85                 }
86             }
87         }
88         
89         return true;
90         
91     }
92 };