zoukankan      html  css  js  c++  java
  • Leetcode: Validate IP Address

    In this problem, your job to write a function to check whether a input string is a valid IPv4 address or IPv6 address or neither.
    
    IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots ("."), e.g.,172.16.254.1;
    
    Besides, you need to keep in mind that leading zeros in the IPv4 is illegal. For example, the address 172.16.254.01 is illegal.
    
    IPv6 addresses are represented as eight groups of four hexadecimal digits, each group representing 16 bits. The groups are separated by colons (":"). For example, the address 2001:0db8:85a3:0000:0000:8a2e:0370:7334 is a legal one. Also, we could omit some leading zeros among four hexadecimal digits and some low-case characters in the address to upper-case ones, so 2001:db8:85a3:0:0:8A2E:0370:7334 is also a valid IPv6 address(Omit leading zeros and using upper cases).
    
    However, we don't replace a consecutive group of zero value with a single empty group using two consecutive colons (::) to pursue simplicity. For example, 2001:0db8:85a3::8A2E:0370:7334 is an invalid IPv6 address.
    
    Besides, you need to keep in mind that extra leading zeros in the IPv6 is also illegal. For example, the address 02001:0db8:85a3:0000:0000:8a2e:0370:7334 is also illegal.
    
    Note: You could assume there is no extra space in the test cases and there may some special characters in the input string.
    
    Example 1:
    Input: "172.16.254.1"
    
    Output: "IPv4"
    
    Explanation: This is a valid IPv4 address, return "IPv4".
    Example 2:
    Input: "2001:0db8:85a3:0:0:8A2E:0370:7334"
    
    Output: "IPv6"
    
    Explanation: This is a valid IPv6 address, return "IPv6".
    Example 3:
    Input: "256.256.256.256"
    
    Output: "Neither"
    
    Explanation: This is neither a IPv4 address nor a IPv6 address.

    Be careful, split() will not include trailing empty strings in the result array

    The string "boo:and:foo", for example, split(":")的结果是 {“boo”, "and", "foo"}; Trailing empty strings are not included in the resulting array.比如,split("o")的结果是{“b”, "", ":and:f"}

    If there exist extra ":" or "." at the end of the string, directly return false

     1 public class Solution {
     2     public String validIPAddress(String IP) {
     3         if (IP==null || IP.length()==0) return "Neither";
     4         boolean isIP4 = checkIP4(IP);
     5         boolean isIP6 = checkIP6(IP);
     6         if (isIP4) return "IPv4";
     7         if (isIP6) return "IPv6";
     8         return "Neither";
     9     }
    10     
    11     public boolean checkIP4(String IP) {
    12         if (IP.charAt(IP.length()-1) == '.') return false;
    13         String[] numbers = IP.split("\.");
    14         if (numbers==null || numbers.length!=4) return false;
    15         for (String str : numbers) {
    16             if (str.length()==0 || str.length()>3) return false;
    17             if (str.length()>1 && str.charAt(0)=='0') return false;
    18             int val = 0;
    19             for (int i=0; i<str.length(); i++) {
    20                 char c = str.charAt(i);
    21                 if (c<'0' || c>'9') return false;
    22                 val = val*10 + (int)(c-'0');
    23             }
    24             if (val<0 || val>255) return false;
    25         }
    26         return true;
    27     }
    28     
    29     public boolean checkIP6(String IP) {
    30         if (IP.charAt(IP.length()-1) == ':') return false;
    31         String[] numbers = IP.split(":");
    32         if (numbers==null || numbers.length!=8) return false;
    33         for (String str : numbers) {
    34             if (str.length()==0 || str.length()>4) return false;
    35             int i = 0;
    36             while (i < str.length()) {
    37                 char c = str.charAt(i++);
    38                 if ((c<'0' || c>'9') && (c<'a' || c>'f') && (c<'A' || c>'F')) return false;
    39             }
    40         }
    41         return true;
    42     }
    43 }
  • 相关阅读:
    html页面,左边点击链接,右边显示内容参考代码。
    下拉列表,鼠标移动上去改变颜色
    js生成验证码
    SAP MM模块之批次管理
    SAP 通过屏幕字段查看透明表
    SAP SD你要知道的透明表
    ]sap透明表、结构、簇介绍以及查找表方法
    设计模式(策略模式)
    设计模式(状态模式)
    设计模式(观察者模式)
  • 原文地址:https://www.cnblogs.com/EdwardLiu/p/6213521.html
Copyright © 2011-2022 走看看