17. Letter Combinations of a Phone Number(C++)

电话号码字母组合生成
本文介绍了一种通过递归方式生成电话号码对应的所有可能字母组合的方法。利用C++实现了一个解决方案,该方案能够处理输入的数字字符串,并返回所有可能的字母组合。此算法适用于电话键盘上数字到字母的映射问题。

Solution :
 1 class Solution {
 2 public:
 3     vector<string> letterCombinations(string digits) {
 4        if(digits.empty()) return vector<string>();
 5        vector<string> list={"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
 6        vector<string> res;
 7        res.push_back("");
 8        for(int i=0;i<digits.size();i++){
 9            if(digits[i]>'9'||digits[i]<'0') continue;
10            int num=digits[i]-'0';
11            vector<string> tmp;
12            for(int k=0;k<list[num].size();k++){
13                for(int j=0;j<res.size();++j){
14                    tmp.push_back(res[j]+list[num][k]);
15                }
16            }
17            res.swap(tmp);
18        }
19        return res;
20     }
21 };

 

转载于:https://www.cnblogs.com/devin-guwz/p/6506672.html

(Telephone Number Word Generator) Standard telephone keypads contain the digits 0 through 9. The numbers 2 through 9 each have three letters associated with them, as is indicated by the following table: Many people find it difficult to memorize phone numbers, so they use the correspondence between digits and letters to develop seven-letter words that correspond to their phone numbers. For example, a person whose telephone number is 686-2377 might use the correspondence indi- cated in the above table to develop the seven-letter word “NUMBERS.” Businesses frequently attempt to get telephone numbers that are easy for their clients to remember. If a business can advertise a simple word for its customers to dial, then no doubt the business will receive a few more calls. Each seven-letter word corresponds to exactly one seven-digit telephone number. The restaurant wishing to increase its take-home business could surely do so with the number 825-3688 (i.e., “TAKEOUT”). Each seven-digit phone number corresponds to many separate seven-letter words. Unfortunately, most of these represent unrecognizable juxtaposi- tions of letters. It’s possible, however, that the owner of a barber shop would be pleased to know that the shop’s telephone number, 424-7288, corresponds to “HAIRCUT.” A veterinarian with the phone number 738-2273 would be happy to know that the number corresponds to “PETCARE.” Write a program that, given a seven-digit number, writes to a file every possible seven-letter word corresponding to that number. There are 2187 (3 to the seventh power) such words. Avoid phone numbers with the digits 0 and 1.
06-09
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