Maximum Product Subarray (smarter)

MaximumProductSubarray.swift

 func maxProduct(_ nums: [Int]) -> Int {
    
    guard nums.count > 0 else {
        return 0
    }
    
    var maximum = nums.first!
    var maxPositivEnding = nums.first!
    var minNegativeEnding = nums.first!
    
    for num in nums.dropFirst() {
        if num > 0 {
            maxPositivEnding = max(num, num * maxPositivEnding)
            minNegativeEnding = min(num, num * minNegativeEnding)
        } else {
            let t = maxPositivEnding
            maxPositivEnding = max(num, num * minNegativeEnding  )
            minNegativeEnding = min(num, num * t)
           
        }
        maximum = max(maximum, maxPositivEnding)
    }
    
    
    return maximum
}