leetcode 17.电话号码字母组合

⭐️ 题目描述

---

leetcode链接：https://leetcode.cn/problems/letter-combinations-of-a-phone-number/description/

代码：

class Solution {
public:
    const char * letterCombine(int i) {
        static const char *letter[] = { "" , "" , "abc" , "def" , "ghi" , "jkl" , "mno" , "pqrs" , "tuv" , "wxyz" };
        return letter[i];
    }
    void combine(vector<string>& v, int i, string curCombine, string& digits) {
        if (i == digits.size()) {
            v.push_back(curCombine);    // 添加
            return;
        }

        int num = digits[i] - '0';
        string s = letterCombine(num);
        for (auto val : s) {
            combine(v, i + 1, curCombine + val, digits);
        }
    }

    vector<string> letterCombinations(string digits) {
        vector<string> v;
        if (digits.empty())  // 空直接返回
            return v;

        string curCombine;  // 用来存储当前组合
        combine(v, 0, curCombine, digits);

        return v;
    }
};

---