class Solution {
func validMountainArray(_ arr: [Int]) -> Bool {
var prev: Int = arr[0]
var up: Bool = true
if arr.count == 1 {
return false
}
if arr.count > 1 {
if arr[1] < arr[0] {
return false
}
}
for i in 1..<arr.count {
if arr[i] == prev {
return false
}
if up {
if arr[i] < prev {
up = false
}
} else {
if arr[i] > prev {
return false
}
}
prev = arr[i]
}
return up == false
}
}