A message containing letters from A-Z is being encoded to numbers using the following mapping:
'A' -> 1'B' -> 2...'Z' -> 26
Given an encoded message containing digits, determine the total number of ways to decode it.
For example,
Given encoded message"12", it could be decoded as "AB" (1 2) or "L" (12). The number of ways decoding "12" is 2.
规律题，总结规律即可：
package mainimport ( "fmt" "strconv")//只需要判断双位数的情况func is_suit_num(num int) bool { if num >= 10 && num <= 26 { return true } else { return false }}func char_style_num(char string) int { length := len(char) if length < 2 { return 1 } num := char[0:2] num_int, _ := strconv.Atoi(num) if is_suit_num(num_int) { return char_style_num(char[1:]) + char_style_num(char[2:]) } else { return char_style_num(char[1:]) }}func main() { fmt.Printf("%d\n", char_style_num("12")) //1,2;12 = 2 fmt.Printf("%d\n", char_style_num("122")) //1,2,2; //12,2; //1,22; = 3 fmt.Printf("%d\n", char_style_num("1221")) //1,2,2,1; //12,2,1; //12,21; //1,22,1; //1,2,21; = 5 fmt.Printf("%d\n", char_style_num("3121")) //3,1,2,1; //3,12,1; //3,1,21; = 3 //-------------------- 总结出规律 ---------------------- // // if arr[N:N-1] suit // F(N) = F(N-1) + F(N-2) // else // F(N) = F(N-1)} 程序输出结果:
2 3 5 3