leetcode-algorithms-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.

解法

通过数字对应的字符串,循环.

class Solution

{

public:

    vector<string> letterCombinations(string digits)

    {

        std::vector<std::string> result;

        if (digits.empty()) return result;

        result = {""};

        std::vector<std::string> v = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};

        for(int i = 0 ; i < digits.size(); ++i)

        {

            int num = digits[i] - '0';

            if(num < 0 || num > 9)

                break;

            std::string cand = v[num];

            if(cand.empty())

                continue;

            std::vector<std::string> tmp = result;

            result.clear();

            for(int j = 0; j < tmp.size(); ++j)

            {

                for(int k = 0; k < cand.size(); ++k)

                    result.push_back(tmp[j] + cand[k]);

            }

        }

        return result;

    }

};

链接: leetcode-algorithms 目录

巴特西

leetcode-algorithms-17 Letter Combinations of a Phone Number

leetcode-algorithms-17 Letter Combinations of a Phone Number

解法

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