leetcode 93. Restore IP Addresses

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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)

class Solution {int my_atoi(string s){int re = 0;int k = 0;while (k <s.length()){re = 10 * re + s[k] - '0';k++;}return re;}public:vector<string> restoreIpAddresses(string s) {vector<string>re;vector< string>candi; vector<string>aa;candi.push_back(s);int k = 0;while (true){vector<string>newcandi;k++;for (int i = 0; i < candi.size(); i++){if (k == 1){for (int j = 1; j <= 3; j++){string ss = candi[i];if (ss.length() - j >= 3 && ss.length() - j <= 9){int n = my_atoi(string(ss.begin(), ss.begin() + j));if ( n <= 255){if ((n == 0 && j == 1)||(n>0&&ss[0]!='0')){ss.insert(ss.begin() + j, '.');newcandi.push_back(ss);}}}}}else if (k == 2){for (int j = 1; j <= 3; j++){string ss = candi[i];int pos = ss.rfind('.');if (ss.length() - j-pos-1 >= 2 && ss.length() - j -pos-1<= 6){int n = my_atoi(string(ss.begin() + pos + 1, ss.begin() + pos + 1 + j));if (n <= 255 ){if ((n == 0 && j == 1) || (n > 0 && ss[pos + 1] != '0')){ss.insert(ss.begin() + pos + j + 1, '.');newcandi.push_back(ss);}}}}}else if (k == 3){for (int j = 1; j <= 3; j++){string ss = candi[i];int pos = ss.rfind('.');if (ss.length() - j -pos-1>= 1 && ss.length() - j-pos-1 <= 3){int n = my_atoi(string(ss.begin() + pos + 1, ss.begin() + pos + 1 + j));int n2 = my_atoi(string(ss.begin() + 1 + j + pos, ss.end()));if (n <= 255 && n2 <= 255){if (((n == 0 && j == 1) || (n > 0 && ss[pos + 1] != '0')) &&((n2 == 0 && 1 + j + pos == ss.length() - 1) || (n2>0 && ss[1 + j + pos] != '0'))){ss.insert(ss.begin() + pos + j + 1, '.');re.push_back(ss);}}}}}}candi = newcandi;if (k == 3)return re;}}};

accepted

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