939. Minimum Area Rectangle

    func minAreaRect(_ points: [[Int]]) -> Int {
        var map = [Int: Set<Int>]()
        //build row - point list
        for p in points {
            map[p[0], default : Set<Int>()].insert(p[1])
        }
        let rows = map.keys.sorted()
        var res = Int.max
        for i in 0 ..< rows.count - 1{
            let row = rows[i]
            let list = Array(map[row]!).sorted()   // get the array sorted
            for j in 0 ..< list.count - 1 {
                for k in j + 1 ..< list.count {
                   for nexti in i + 1 ..< rows.count{
                       let nextRow = rows[nexti]
                       let nextSet = map[nextRow]!
                       if nextSet.contains(list[j]) && nextSet.contains(list[k]){
                           res = min(res, (nextRow - row) * (list[k] - list[j]) )
                       }
                   }
                }
            }
        }
        if res == Int.max {return 0}
        return res
    }