855. Exam Room

class ExamRoom {

    var sit = [Int]()
    let maxEnd : Int
    init(_ N: Int) {
        maxEnd = N
    }

    func seat() -> Int {
        if sit.count == 0 {
            sit.append(0)
            return 0
        }

        var maxLenth = 0
        var res = -1
        if !sit.contains(0){ //0没有用过
            maxLenth = sit[0] - 0
            res = 0
        }

        var left = 0
        var runner = left + 1
        while runner < sit.count{

            let len = (sit[runner] - sit[left] ) / 2

            if len > maxLenth{
                maxLenth = len
                res =  (sit[runner] + sit[left] ) / 2
            }
            left = runner
            runner += 1
        }

        if !sit.contains(maxEnd - 1){ //0没有用过
            let len = (maxEnd  - 1 - sit.last!)

            print(maxLenth)
            if len > maxLenth{
                res =  maxEnd - 1
            }
        }
        sit.append(res)
        sit.sort()
        return res
    }

    func leave(_ p: Int) {
        sit = sit.filter{$0 != p}
        // print(sit)
    }
}