Package g1901_2000.s1922_count_good_numbers

Class Solution

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

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 Details

Solution

public Solution()

Method Details

countGoodNumbers

public int countGoodNumbers(long n)