leetcode

0 class Solution {

1 bool valid(const string &s) {

2 if (s.empty()) return true;

3 return stoi(s) >= 0 && stoi(s) <= 255;

4 }

5

6 public:

7 vector<string> restoreIpAddresses(string s) {

8 int n = s.size();

9

10 vector<string> res;

11 string s1, s2, s3, s4;

12 bool e4;

13

14 s1 = "";

15 for (int i = 0; i < n; i++) {

16 s1 += s[i], s2 = "";

17 if (!valid(s1)) break;

18 for (int j = i + 1; j < n; j++) {

19 s2 += s[j], s3 = "";

20 if (!valid(s2)) break;

21 for (int k = j + 1; k < n; k++) {

22 s3 += s[k], s4 = "";

23 if (!valid(s3)) break;

24 for (int l = k + 1; l < n; l++) {

25 s4 += s[l], e4 = false;

26 if (!valid(s4) || (s4.size() >= 2 && s4.front() == '0')) {

27 e4 = true;

28 break;

29 }

30 }

31 if (!e4 && !s4.empty()) res.push_back(s1 + "." + s2 + "." + s3 + "." + s4);

32 if (s3.front() == '0') break;

33 }

34 if (s2.front() == '0') break;

35 }

36 if (s1.front() == '0') break;

37 }

38 return res;

39 }

40 };