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  • 17. Letter Combinations of a Phone Number

    Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

    A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.

    Example:

    Input: "23"
    Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].
    

    Note:

    Although the above answer is in lexicographical order, your answer could be in any order you want.

    AC code:

    class Solution {
    public:
        vector<string> letterCombinations(string digits) {
            vector<string> res;
            if (digits.length() == 0) return res;
            vector<string> num_map = {"0", "1", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
            res.push_back("");
            for (int i = 0; i < digits.length(); ++i) {
                vector<string> tem;
                string str = num_map[digits[i]-'0'];
                for (int j = 0; j < str.length(); ++j) {
                    for (int k = 0; k < res.size(); ++k) {
                        tem.push_back(res[k] + str[j]);
                    }
                }
                res = tem;
            }
            sort(res.begin(), res.end());
            return res;
        }
    };
    
    Runtime: 0 ms, faster than 100.00% of C++ online submissions for Letter Combinations of a Phone Number.
    永远渴望,大智若愚(stay hungry, stay foolish)
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  • 原文地址:https://www.cnblogs.com/h-hkai/p/9740902.html
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