规范格式

leetcode/0017.Letter-Combinations-of-a-Phone-Number/17. Letter Combinations of a Phone Number.go

@@ -0,0 +1,39 @@
+package leetcode
+
+var (
+	letterMap = []string{
+		" ",    //0
+		"",     //1
+		"abc",  //2
+		"def",  //3
+		"ghi",  //4
+		"jkl",  //5
+		"mno",  //6
+		"pqrs", //7
+		"tuv",  //8
+		"wxyz", //9
+	}
+	res = []string{}
+)
+
+func letterCombinations(digits string) []string {
+	if digits == "" {
+		return []string{}
+	}
+	res = []string{}
+	findCombination(&digits, 0, "")
+	return res
+}
+
+func findCombination(digits *string, index int, s string) {
+	if index == len(*digits) {
+		res = append(res, s)
+		return
+	}
+	num := (*digits)[index]
+	letter := letterMap[num-'0']
+	for i := 0; i < len(letter); i++ {
+		findCombination(digits, index+1, s+string(letter[i]))
+	}
+	return
+}