概述
给出一个由一些数字组成的输入字符串。数字与字母的映射类似于电话键盘的映射。
2 = either "a", "b" or "c"
3 = either "d", "e" or "f"
4 = either "g", "h" or "i"
5 = either "j", "k" or "l"
6 = either "m", "n" or "co"
7 = either "p", "q" "r" or "s"
8 = either "t", "u" or "v"
9 = either "w", "x", "y" or "z"
所以给定一个只由数字组成的输入字符串。其目的是返回所有的字母组合
例子
Input: "3"
Output: [d e f]
Input: "34"
Output: [dg dh di eg eh ei fg fh fi]
Input: "345"
Output: [dgj dgk dgl dhj dhk dhl dij dik dil egj egk egl ehj ehk ehl eij eik eil fgj fgk fgl fhj fhk fhl fij fik fil]
程序
以下是相同的程序。
package main
import "fmt"
func letterCombinations(digits string) []string {
if digits == "" {
return nil
}
letterMap := make(map[string][]string)
letterMap["2"] = []string{"a", "b", "c"}
letterMap["3"] = []string{"d", "e", "f"}
letterMap["4"] = []string{"g", "h", "i"}
letterMap["5"] = []string{"j", "k", "l"}
letterMap["6"] = []string{"m", "n", "o"}
letterMap["7"] = []string{"p", "q", "r", "s"}
letterMap["8"] = []string{"t", "u", "v"}
letterMap["9"] = []string{"w", "x", "y", "z"}
runeDigits := []rune(digits)
length := len(runeDigits)
temp := ""
return letterCombinationsUtil(runeDigits, 0, length, temp, letterMap)
}
func letterCombinationsUtil(runeDigits []rune, start, length int, temp string, letterMap map[string][]string) []string {
if start == length {
return []string{temp}
}
currentDigit := string(runeDigits[start])
letters := letterMap[currentDigit]
final := make([]string, 0)
for _, val := range letters {
t := temp + val
output := letterCombinationsUtil(runeDigits, start+1, length, t, letterMap)
final = append(final, output...)
}
return final
}
func main() {
output := letterCombinations("3")
fmt.Println(output)
output = letterCombinations("34")
fmt.Println(output)
output = letterCombinations("345")
fmt.Println(output)
}
输出
[d e f]
[dg dh di eg eh ei fg fh fi]
[dgj dgk dgl dhj dhk dhl dij dik dil egj egk egl ehj ehk ehl eij eik eil fgj fgk fgl fhj fhk fhl fij fik fil]
