题解 | #验证IP地址#
验证IP地址
https://www.nowcoder.com/practice/55fb3c68d08d46119f76ae2df7566880
这道题要考虑完全属实有些伤脑筋，全靠调试
import java.util.*;
public class Solution {
/**
* 验证IP地址
* @param IP string字符串 一个IP地址字符串
* @return string字符串
*/
public String solve (String ip) {
// write code here
int lg = ip.length();
if(lg<=15){
return checkIPv4(ip)?"IPv4":"Neither";
}else{
return checkIPv6(ip)?"IPv6":"Neither";
}
}
public boolean checkIPv4(String ip){
String[] str = ip.split("\\.");
if(str.length !=4) return false;
for(String s : str){
if(!checkNum4(s.toCharArray(),0)||String.valueOf(Integer.valueOf(s)).length()<s.length())return false;
}
return Integer.valueOf(str[0]) <= 255 && Integer.valueOf(str[1]) <= 255 && Integer.valueOf(str[2]) <= 255 && Integer.valueOf(str[3]) <= 255;
}
public boolean checkIPv6(String ip){
char[] w= ip.toCharArray();
int count=0;
for(char c : w)if(c == ':')count++;
if(count>7)return false;
String[] str = ip.split(":");
if(str.length !=8) return false;
for(String s : str){
if(checkNum6(s.toCharArray(),0)==false||(!s.equals("0")&&s.length()!=4))return false;
}
return true;
}
public boolean checkNum6(char[] num,int i){
if(i>=num.length)return true;
if(num.length>4 || (Character.isDigit(num[i])==false&&Character.isLetter(num[i])==false))return false;
//&& (?(?true:false):(num[i]<='F'?true:false))
if(Character.isLowerCase(num[i]) && num[i] >'f') return false;
if(Character.isUpperCase(num[i]) && num[i] > 'F')return false;
return (Character.isDigit(num[i])||Character.isLetter(num[i]))&&checkNum6(num,i+1);
}
public boolean checkNum4(char[] num,int i){
if(i>=num.length)return true;
if(num.length>3 || Character.isDigit(num[i])==false)return false;
return Character.isDigit(num[i]) && checkNum4(num,i+1);
}
}
