Solution (leetcode-in-java 1.23 API)

java.lang.Object
- g1901_2000.s1922_count_good_numbers.Solution

```
public class Solution
extends Object
```
1922 - Count Good Numbers.
Medium

A digit string is good if the digits (0-indexed) at even indices are even and the digits at odd indices are prime (2, 3, 5, or 7).
- For example, "2582" is good because the digits (2 and 8) at even positions are even and the digits (5 and 2) at odd positions are prime. However, "3245" is not good because 3 is at an even index but is not even.
Given an integer n, return the total number of good digit strings of length n. Since the answer may be large, return it modulo 10⁹ + 7.

A digit string is a string consisting of digits 0 through 9 that may contain leading zeros.

Example 1:

Input: n = 1

Output: 5

Explanation: The good numbers of length 1 are “0”, “2”, “4”, “6”, “8”.

Example 2:

Input: n = 4

Output: 400

Example 3:

Input: n = 50

Output: 564908303

Constraints:
- 1 <= n <= 10¹⁵

- Constructor Summary
  
  Constructors
  Constructor Description
  
  Solution()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  int countGoodNumbers(long n)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- Solution
```
public Solution()
```

Method Detail

countGoodNumbers

public int countGoodNumbers(long n)