Given a string containing only digits, restore it by returning all possible valid IP address combinations.
For example: Given “25525511135”,
return [“255.255.11.135”, “255.255.111.35”]. (Order does not matter)
题意：给定一个字符串，判断其代表的IP地址数
解决思路：类似穷举……
代码：
{public List<String> restoreIpAddresses(String s) {List<String> res = new ArrayList<String>();int len = s.length();for(int i = 1; i<4 && i<len-2; i++){for(int j = i+1; j<i+4 && j<len-1; j++){for(int k = j+1; k<j+4 && k<len; k++){String s1 = s.substring(0,i), s2 = s.substring(i,j), s3 = s.substring(j,k), s4 = s.substring(k,len);if(isValid(s1) && isValid(s2) && isValid(s3) && isValid(s4)){res.add(s1+”.”+s2+”.”+s3+”.”+s4);}}}}return res;}(String s){if(s.length()>3 || s.length()==0 || (s.charAt(0)==’0′ && s.length()>1) || Integer.parseInt(s)>255)return false;return true;}}
，或许人生就是一场旅行，在旅行中遇到的每一个人，
