将字符 c[i] 和 c[x] 交换，即固定 c[i] 为当前位字符；
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| func permutation(s string) []string {
var res []string
combinations(nil,0,[]byte(s),&res)
return res
}
func combinations(current []byte, index int,src []byte, res *[]string){
var encountered = make(map[byte]struct{},0)
if index >= len(src){
*res = append(*res,string(current))
return
}
for i:=index ; i<len(src); i++{
if _,ok := encountered[src[i]];ok{
continue
}
currentByte := src[i]
encountered[currentByte] = struct{}{}
src[i],src[index] = src[index],src[i]
current = append(current,currentByte)
combinations(current,index+1,src,res)
src[i],src[index] = src[index],src[i]
current = current[:len(current)-1]
}
return
}
|
