package top100liked

import (
	"fmt"
	"testing"
)

// https://leetcode.cn/problems/letter-combinations-of-a-phone-number?envType=study-plan-v2&envId=top-100-liked

var m = map[byte][]byte{
	'2': []byte("abc"),
	'3': []byte("def"),
	'4': []byte("ghi"),
	'5': []byte("jkl"),
	'6': []byte("mno"),
	'7': []byte("pqrs"),
	'8': []byte("tuv"),
	'9': []byte("wxyz"),
}

func letterCombinations(digits string) []string {
	res := []string{}

	var helper func(idx int, r []byte)
	helper = func(idx int, r []byte) {
		if idx == len(digits) {
			res = append(res, string(r))
			return
		}
		for j := range m[digits[idx]] {
			r = append(r, m[digits[idx]][j])
			helper(idx+1, r)
			r = r[:len(r)-1]
		}
	}

	helper(0, []byte{})
	return res
}

func Test(t *testing.T) {
	fmt.Printf("%+v", letterCombinations("23"))
	fmt.Printf("%+v", letterCombinations("2"))
}