题目：
468. Validate IP Address(medium)
解题思路：
代码：1
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47public String validIPAddress(String IP) {
if(IP == null || IP.length() == 0) return "Neither";
String[] IP4Addr = IP.split("\\.",-1);//-1会保留空值
if(IP4Addr.length == 4){
return isIP4Addr(IP4Addr);
}
String[] IP6Addr = IP.split(":",-1);
if(IP6Addr.length == 8){
return isIP6Addr(IP6Addr);
}
return "Neither";
}
private String isIP4Addr(String[] IP4Addr){
for(String ip : IP4Addr){
if(ip.length() > 3 || ip.length() <= 0){
return "Neither";
}
for(int i = 0;i < ip.length();++i){
if(!Character.isDigit(ip.charAt(i))){
return "Neither";
}
}
int num = Integer.parseInt(ip);
if(num > 255 || String.valueOf(num).length() != ip.length()){
return "Neither";
}
}
return "IPv4";
}
private String isIP6Addr(String[] IP6Addr){
for(String ip : IP6Addr){
if(ip.length() > 4 || ip.length() <= 0){
return "Neither";
}
for(int i = 0;i < ip.length();i++){
char c = ip.charAt(i);
if(!Character.isDigit(c) && !('a' <= c && c <= 'f' ) && !('A' <= c && c <= 'F')){
return "Neither";
}
}
}
return "IPv6";
}
