|
给一个数字字符串，每个数字代表一个字母，请返回其所有可能的字母组合。
下图的手机按键图，就表示了每个数字可以代表的字母。
样例
给定 "23"
返回 ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]
class Solution {
public:
void init(){
node['2'].push_back('a');
node['2'].push_back('b');
node['2'].push_back('c');
node['3'].push_back('d');
node['3'].push_back('e');
node['3'].push_back('f');
node['4'].push_back('g');
node['4'].push_back('h');
node['4'].push_back('i');
node['5'].push_back('j');
node['5'].push_back('k');
node['5'].push_back('l');
node['6'].push_back('m');
node['6'].push_back('n');
node['6'].push_back('o');
node['7'].push_back('p');
node['7'].push_back('q');
node['7'].push_back('r');
node['7'].push_back('s');
node['8'].push_back('t');
node['8'].push_back('u');
node['8'].push_back('v');
node['9'].push_back('w');
node['9'].push_back('x');
node['9'].push_back('y');
node['9'].push_back('z');
}
void letterCombinations(const string &s,int length,int pos){
if(pos==length){
ret.push_back(base);
return ;
}
vector<char> &tmp=node[s[pos]];
int size=tmp.size();
for(int i=0;i<size;++i){
base.push_back(tmp[i]);
letterCombinations(s,length,pos+1);
base.pop_back();
}
}
vector<string> letterCombinations(string& digits) {
if(digits.empty())
return ret;
init();
letterCombinations(digits,digits.length(),0);
return ret;
}
private :
vector<string> ret;
string base;
map<char,vector<char> > node;
};
| 
转播
