leetcode 17. Letter Combinations of a Phone Number

题意：手机上每个数字键都有几个字符，给你一串数字，让你去找到打出字符的所有可能。

题解：此题比较简单，就是一个简单的全排列问题

#include 
#include 
#include 
using namespace std;

void letterCombinations(vector& pos, string dights, string currStr, int index, vector& pho){
    if (index == dights.size()){
        if (currStr.size() != 0) pos.push_back(currStr);
        return;
    }

    string temp = pho[dights[index] - '0'];
    for (int i = 0;i < temp.size();i++){
        string newCurr = currStr + temp[i];
        letterCombinations(pos, dights, newCurr, index + 1, pho);
    }
}


vector letterCombinations(string dights) {
    vector pho = {"", "", "abc", "def", "ghi", "jkl","mno", "pqrs", "tuv", "wxyz"};
    vector pos ;

    letterCombinations(pos, dights, "", 0, pho);
    return pos;

}
int main(){
    string dights = "23";
    vector strs = letterCombinations(dights);
    for (int i = 0 ;i < strs.size();i++)
        cout << strs[i] << endl;
}