func longestConsecutive(nums []int) int {
    numSet:=map[int]bool{}
    for _,v:=range nums {
        numSet[v] = true
    }
    longest := 0

   for num:=range numSet {
       if numSet[num - 1] {
           continue
       }
       cur :=num
       for numSet[cur+1] {
           cur++
       }
       longest = max(longest,cur - num + 1)
   }
    return longest
}
func max(a, b int)int{
    if a > b{
        return a
    }
    return b
}