House 链接问题

struct House{
    let id : Int
    let left : Int
    let right : Int
    init(_ id: Int, _ left: Int, _ right: Int) {
        self.id = id
        self.left = left
        self.right = right
    }
}

func getBlock(_ arr: [House]) -> Int{
    var visited = Set<Int>()
    var count = arr.count
    for house in arr{
        if visited.contains(house.left) { count -= 1}
        if visited.contains(house.right) { count -= 1}
        visited.insert(house.id)
    }
    return count
}

let h3 = House(3, 2,4)
//let h2 = House(2, 1,3)
let h1 = House(1, 0,2)
let h7 = House(7, 6,8)

let arr = [h1,h3,h7]

print(getBlock(arr))