Letter Combinations of a Phone Number

最新推荐文章于 2025-08-23 02:01:11 发布

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本文详细介绍了如何通过给定的数字字符串，利用预定义的按键映射表，生成对应的字母组合。通过循环遍历输入字符串的每个字符，根据其对应字母数量更新结果集，最终返回所有可能的字母组合序列。

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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.

没意思。。。。vector update自己的时候每次是原来次数乘以新数字的可能字母的size....所以要用一个tmp在loop的时候装result...

class Solution {
public:
  vector<string> letterCombinations(string digits) {
    static string querry[]={"abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
    vector<string> result={""};
    for (int i=0; i<digits.size();i++){
      char c=digits[i];
      vector<string> tmp;
      string local=querry[c-'2'];
      for (int j=0; j<local.size(); j++) {
	    for (int k=0; k<result.size();k++){
	    string a=result[k]+local[j];
	    tmp.push_back(a);
    	}
      }
      result=tmp;
    }
    return result;
  }
};