LeetCode *** 17. Letter Combinations of a Phone Number

最新推荐文章于 2025-05-25 20:50:12 发布

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最新推荐文章于 2025-05-25 20:50:12 发布

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本文介绍了一种算法，用于根据电话按键上的字母映射，找出所有可能的字母组合。输入为一串数字，输出为所有可能的字母组合列表。

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题目：

Given a digit string, 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.

Input:Digit string "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.

分析：

“你是一封信我是邮差，忙着去护送来不及拆开，里面完美的世界～”。。

代码：

class Solution {
public:
    vector<string> letterCombinations(string digits) {
        if(digits.length()<1)return vector<string>();
        
        string d[] = {"", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"};
        
        vector<string> res({""});
        
        for(int i=0;i<digits.size();++i){
            
            vector<string> tmp;
            for(int j=0;j<d[digits[i]-'0'].length();++j)
                for(int k=0;k<res.size();++k)
                    tmp.push_back(res[k]+d[digits[i]-'0'][j]);
            res=tmp;
        }
        return res;
        
    }
};