문제로 이동

풀이

let word = readLine()!.uppercased()
var splitted: [Character] = []

word.forEach { character in
    splitted.append(character)
}

let alphabetSet: Set<Character> = Set(splitted)
var counted: [Character: Int] = [:]

for alphabet in alphabetSet {
    let number = splitted.filter { character in
        return alphabet == character
    }.count
    counted[alphabet] = number
}

let filtered = counted.filter { dictionary in
    return dictionary.value == counted.values.max()!
}

if filtered.count == 1 {
    print(filtered.first!.key)
} else {
    print("?")
}

사용한 개념

• Dictionary
• Set
• filter