LEETCODE: Restore IP Addresses

最新推荐文章于 2025-11-25 00:06:26 发布

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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)

忍不住又做了一题！

class Solution {
public:
    void getAddresses(vector<string> &results, string s, string temp, int segment) {
        if(s.length() < segment) return;
        if(segment == 1) {
            if(s.length() >= 2 && s[0] == '0') return;
            if(s.length() < 3 || (s.length() == 3 && s <= "255"))
                results.push_back(temp + "." + s); 
            return;
        }
        
        string s0(s, 0, 1);
        if(s.length() - 1 <= (segment - 1) * 3) {
            string newstr = temp + (segment == 4 ? "" : ".");
            newstr += s0;
            getAddresses(results, s.substr(1, s.length() - 1), newstr, segment - 1);
        }
        
		if(s[0] == '0')
			return;

        string s1(s, 0, 2);
        if(s.length() - 2 <= (segment - 1) * 3) {
            string newstr = temp + (segment == 4 ? "" : ".");
            newstr += s1;
            getAddresses(results, s.substr(2, s.length() - 2), newstr, segment - 1);
        }
        
		if(s[0] == '0' && s[1] == '0')
			return;
        string s2(s, 0, 3);
        if(s.length() - 3 <= (segment - 1) * 3 && s2 <= "255") {
            string newstr = temp + (segment == 4 ? "" : ".");
            newstr += s2;
            getAddresses(results, s.substr(3, s.length() - 3), newstr, segment - 1);
        }
    }
    vector<string> restoreIpAddresses(string s) {
        if(s.length() < 3 || s.length() > 12) return vector<string>();
        vector<string> results;
        string temp;
        getAddresses(results, s, temp, 4);
        return results;
    }
};