lc320

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Write a function to generate the generalized abbreviations of a word.

Example:

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Given word = "word", return the following list (order does not matter):
["word", "1ord", "w1rd", "wo1d", "wor1", "2rd", "w2d", "wo2", "1o1d", "1or1", "w1r1", "1o2", "2r1", "3d", "w3",

backtracking

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class Solution {
    unordered_map<string, vector<string>> mp;
public:
    vector<string> generateAbbreviations(string word) {
        string s = "";
        mp[""].push_back("");
        helper(word);
        return mp[word];
    }
    vector<string> helper(string s) {
        string res = "";
        if (mp.find(s) != mp.end())
            return mp[s];
        int len = s.length();
        res += s[0];
        vector<string> rem = helper(s.substr(1));
        for (auto rest: rem) {
            mp[s].push_back(res+rest);
        }
        for (int i = 0; i < len; i++) {
            res = to_string(i+1);
            if (i < len-1) {
                res += s[i+1];
                vector<string> rem = helper(s.substr(i+2));
                for (auto rest: rem) 
                    mp[s].push_back(res+rest);
            }
            else mp[s].push_back(res);
        }
        return mp[s];
    }
};