LeetCodehot100-17电话号码的字母组合

class Solution { private: string st[10]{,,abc,def,ghi,jkl,mno,pqrs,tuv,wxyz}; vectorchar path;//路径 public: void backtrack(vectorstring res,string digits,int f,int sz){ if(fsz){ res.push_back(string(path.begin(), path.end())); return; } //枚举第f个字母是什么 for(auto c : st[digits[f] - 0]){ path.push_back(c); backtrack(res,digits,f1,sz); path.pop_back(); } } vectorstring letterCombinations(string digits) { int szdigits.size(); if (sz0){ return {}; } vectorstring res; backtrack(res,digits,0,sz); return res; } };