LeetCode Letter Combinations of a Phone Number 电话号码组合

 

 

题意：给一个电话号码，要求返回所有在手机上按键的组合，组合必须由键盘上号码的下方的字母组成。

思路：尼玛，一直RE，题意都不说0和1怎么办。DP解决。

 

 

class Solution {
public:
    vector<string> ans;
    string str;

    void DFS(const string sett[], int siz, string t )
    {
        int n=str[siz]-'0';
        if(siz==str.size()){ans.push_back( t );return ;}
        for(int i=0; i<sett[n].size(); i++)    DFS(sett, siz+1, t+sett[n][i] );
    }

    vector<string> letterCombinations(string digits) {
        if(digits.empty())  return vector<string> ();
        str=digits;
        const string mapp[]={"0","1","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
        DFS(mapp, 0, "");
        return ans;
    }
};