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import Foundation
/*
Perl Weekly Challenge - 072
Task #1: Trailing Zeroes
https://perlweeklychallenge.org/blog/perl-weekly-challenge-072
*/
enum ParamError: Error {
case missingNumber
case invalidNumber
}
do {
let paramCount:Int = Int(CommandLine.argc)
if paramCount <= 1 {
throw ParamError.missingNumber
}
let number:Int = Int(CommandLine.arguments[1])!
if number <= 0 || number > 10 {
throw ParamError.invalidNumber
}
print(countTrailingZeroes(calculateFactorial(number)))
}
catch ParamError.missingNumber {
print("Missing number.")
}
catch ParamError.invalidNumber {
print("Invalid number.")
}
catch let error {
print(error)
}
//
//
// Functions
func calculateFactorial(_ number:Int) -> String {
var n:Int = number
for i in 1..<n {
n = n * i
}
return String(n)
}
func countTrailingZeroes(_ factorial:String) -> Int {
let pattern = "^[1-9]+?(?<zero>[0]+)$"
let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive)
if let match = regex?.firstMatch(
in: factorial,
options: [],
range: NSRange(location: 0,
length: factorial.utf16.count)) {
if let zeroMatch = Range(match.range(withName: "zero"), in: factorial) {
return factorial[zeroMatch].count
}
}
return 0
}
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