## README ¶

### 639. Decode Ways II

#### 题目

A message containing letters from `A-Z`

is being encoded to numbers using the following mapping way:

```
'A' -> 1
'B' -> 2
...
'Z' -> 26
```

Beyond that, now the encoded string can also contain the character '*', which can be treated as one of the numbers from 1 to 9.

Given the encoded message containing digits and the character '*', return the total number of ways to decode it.

Also, since the answer may be very large, you should return the output mod 10^9 + 7.

```
Example 1:
Input: "*"
Output: 9
Explanation: The encoded message can be decoded to the string: "A", "B", "C", "D", "E", "F", "G", "H", "I".
Example 2:
Input: "1*"
Output: 9 + 9 = 18
```

Note:

- The length of the input string will fit in range [1, 105].
- The input string will only contain the character '*' and digits '0' - '9'.

#### 解题思路

见程序注释