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//力扣代码
class Solution {const char* numStrArr[10]={"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
public:void Combine(const string& digits,int i,string combineStr,vector<string>& ret){if(i == digits.size()){ret.push_back(combineStr);return;}int num=digits[i]-'0';string str=numStrArr[num];for(auto ch:str)Combine(digits,i+1,combineStr+ch,ret);}vector<string> letterCombinations(string digits) {vector<string> v;if(digits.empty())return v;string str;Combine(digits,0,str,v);return v;}
};

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总结

        例如：以上就是今天要讲的内容，本文仅仅简单介绍了c++的小知识。