Max double slice

max_slice.swift

 public func solution(_ A : inout [Int]) -> Int {
    
    if A.count <=  3 { return 0 }
    // write your code in Swift 3.0 (Linux)
    
    // handle special cases
    var toRight: [Int]  = Array(repeating: 0, count: A.count - 2)
    var toLeft: [Int]   = Array(repeating: 0, count: A.count - 2)
    
    for (index, _) in A.enumerated() {
        
        if index == 0 || index == A.count - 1 { continue }
        
        let leftToRightIndex: Int = index - 1
        
        if index == 1 {
            
            toLeft[leftToRightIndex] = 0
        } else {
            
            toLeft[leftToRightIndex] = max(0, max(A[index - 1], A[index - 1] + toLeft[leftToRightIndex - 1]))
        }
        
        let rightToLeftIndex: Int = toRight.count - index
        
        if rightToLeftIndex == toRight.count - 1 {
            
            toRight[rightToLeftIndex] = 0
        } else {
            
            toRight[rightToLeftIndex] = max(0, max(A[A.count - index - 1 + 1], A[A.count - index - 1 + 1] + toRight[rightToLeftIndex + 1]))
        }
    }
    
    var result: Int = 0
    for (i, item) in toRight.enumerated() {
        
        if toRight[i] + toLeft[i] > result { result = toRight[i] + toLeft[i] }
    }
    
    return result
 }