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Count the Numbers

Problem Description​

Write an extension for collections of integers that returns the number of times a specific digit appears in any of its numbers.

Input​

  • A collection of integers.
  • A specific digit (as a string) to count within the numbers of the collection.

Output​

  • An integer representing the number of times the specified digit appears across all numbers in the collection.

Constraints​

  • The collection will contain non-negative integers.
  • The digit to be counted is a single character string representing a digit ('0'-'9').

Example​

Input:
[5, 15, 55, 515].challenge37(count: "5")

Output:
6

Explanation:
The digit '5' appears 6 times in the numbers [5, 15, 55, 515].

Input:
[5, 15, 55, 515].challenge37(count: "1")

Output:
2

Explanation:
The digit '1' appears 2 times in the numbers [5, 15, 55, 515].

Input:
[55555].challenge37(count: "5")

Output:
5

Explanation:
The digit '5' appears 5 times in the number [55555].

Input:
[55555].challenge37(count: "1")

Output:
0

Explanation:
The digit '1' does not appear in the number [55555].