Practice extention index(like .range)

extentionmemo.swift

import Foundation

extension String {
    func index(character: Character) -> String.Index? {
        let index = self.characters.enumerated().filter { (idx, c) in c == character }.first?.0
        guard let offset = index else {
            return nil
        }
        return self.index(self.startIndex, offsetBy: offset)
    }
}

let line1: String = readLine()!
let n: Int = Int(line1)!

if 0 <= n && n <= 9 {
    let m: Int = Int(readLine()!)!
    if 0 <= m && m <= 100 {
        var array = [Int]()
        for i in 0..<m {
            let line2: String = readLine()!
            let r_i: Int = Int(line2)!
            if 0 <= r_i && m <= 1000 {
                let char = Character(line1)
                if line2.index(character: char) == nil {
                    array.append(r_i)
                }
            }
        }
        
        if array.count != 0 {
            for i in array {
                print(i)
            }
        } else {
            print("none")
        }
    }
}