[코딜리티] 레슨 4 - FrogRiverOne (Swift)

풀이1 : Set의 활용

public func solution(_ X : Int, _ A : inout [Int]) -> Int {
    var leaves = Set<Int>()

    for i in 0..<A.count {
        leaves.insert(A[i])

        if leaves.count == X {
            return i
        }
    }

    return -1
}

풀이2 : Frequency Map의 활용

public func solution(_ X : Int, _ A : inout [Int]) -> Int {
    var frequencyMap: [Int: Bool] = [:]
    for i in 1...X {
        frequencyMap[i] = false
    }

    for i in 0..<A.count {
        frequencyMap[A[i]] = true

        guard !frequencyMap.values.contains(false) else {
            continue
        }
        return i
    }
    return -1
}