For the "almostIncreasingSequence" problem on CodeFights:

AlmostIncreasingSequence.swift

extension Sequence where Element: Comparable {
    func isAlmostIncreasingSequence() -> Bool {
        var foundMisplacedElement = false
        
        for (a, b) in zip(self, self.dropFirst()) where a >= b {
            guard !foundMisplacedElement else { return false }
            
            foundMisplacedElement = true
        }
        
        return true
    }
}

Solves the problem in linear time and constant space