Leetcode 93.Restore IP Addresses (restore IP Address) Thinking and method of solving problems

Given a string containing only digits, restore it is returning all possible valid IP address combinations.

For example:
Given "25525511135" ,

Return ["255.255.11.135", "255.255.111.35"] . (Order does not matter)

Idea: the subject with recursive implementation, an IP address only 3 points, according to the number of points to judge the legal non-law (also is that the string length can only be more than the number of points, and less than k+1), K is the number of points.

If you do not need to add a point at the end, the field value is less than 256, then it is legal to add a result set.

The code is as follows:

public class Solution {list<string> List;    Public list<string> restoreipaddresses (String s) {List = new arraylist<string> ();                /** * The initial incoming string length can only be 4-12 */Adddot (S, "", 3);    return list;     }/** * * @param s string to be processed * @param result loading String * @param k there are currently several "."    */private void Adddot (string s,string result, int k) {//incoming string must be valid if (S.length () <= k) {return;    } if (S.length () > K+1) {return; } if (k = = 0) {//Last paragraph, judging less than (S.charat (0) = = ' 0 ' && s.length () > 1) | |    Integer.parseint (s) >=) return;    List.add (Result + "." + s);    Return }//Traverse the front 3 bits, if less than 256, then participate in recursion for (int i = 1; I <= s.length (); i++) {String temp = s.substring (0,i);//The current segment is less than 256, which means it is legal,    can continue if (Integer.parseint (temp) <) {String str = s.substring (i);    If result is null, the preceding "." is not added.    if (result.length () > 0) {temp = result + "." + temp; } Adddot (Str,temP, k-1);    If the first number is 0, the loop will no longer continue if (S.charat (0) = = ' 0 ') {break;    }}else{break; }    }    }}

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Leetcode 93.Restore IP Addresses (restore IP Address) Thinking and method of solving problems