init commit

archive/algorithm/leetcode/17.go

@@ -0,0 +1,39 @@
+package main
+
+var mapping = map[rune][]rune{
+	'2': {'a', 'b', 'c'}, '3': {'d', 'e', 'f'},
+	'4': {'g', 'h', 'i'}, '5': {'j', 'k', 'l'}, '6': {'m', 'n', 'o'},
+	'7': {'p', 'q', 'r', 's'}, '8': {'t', 'u', 'v'}, '9': {'w', 'x', 'y', 'z'},
+}
+
+func dfs(digits string, ret []string) []string {
+	if digits == "" {
+		return ret
+	}
+	chars := mapping[rune(digits[0])]
+	if len(ret) == 0 {
+		for _, val := range chars {
+			ret = append(ret, string(val))
+		}
+	} else {
+		retLen := len(ret)
+		for key, _ := range ret {
+			for _, val := range chars {
+				ret = append(ret, ret[key]+string(val))
+			}
+		}
+		ret = ret[retLen:]
+	}
+	ret = dfs(digits[1:], ret)
+	return ret
+}
+
+func letterCombinations(digits string) []string {
+	return dfs(digits, []string{})
+}
+
+func main() {
+	for _, val := range letterCombinations("26") {
+		println(val)
+	}
+}