题目描述
给定一个仅包含数字 2-9 的字符串,返回所有它能表示的字母组合。答案可以按 任意顺序 返回。给出数字到字母的映射如下(与电话按键相同)。注意 1 不对应任何字母。
示例 1:
输入:digits = "23"
输出:["ad","ae","af","bd","be","bf","cd","ce","cf"]
0 <= digits.length <= 4
digits[i]
是范围['2', '9']
的一个数字
题目分析
这道题意义不大,就是把对应的字母写好,然后进行枚举即可
class Solution {
public:
string tmp;
vector<string> res;
vector<string> board={"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};//数字对应的字母
void DFS(int pos,string digits){
if(pos==digits.size()){
res.push_back(tmp);
return;
}
int num=digits[pos]-'0';
for(int i=0;i<board[num].size();i++){
tmp.push_back(board[num][i]);
DFS(pos+1,digits);
tmp.pop_back();
}
}
vector<string> letterCombinations(string digits) {
if(digits.size()==0) return res;
DFS(0,digits);
return res;
}
};