2016-04-24 Swift solution to StoneWall

This is a 100% scoring solution to the Codility StoneWall problem. Note the bunch of print statements which I've left included for now.

  //: https://codility.com/programmers/task/stone_wall/
  import UIKit

  public func solution1(inout H : [Int]) -> Int {
    var stack: [Int] = []
    var nBlocks = 0
    var i = 0
    var lastHeight = 0
    
    func append(height: Int) {
      print("append \(height)")
      stack.append(height)
      lastHeight = height
      nBlocks += 1
    }
    
    while i < H.count {
      let currHeight = H[i]
      print("i=\(i), currHeight=\(currHeight)")
      if i == 0 {
        append(currHeight)
      } else {
        if currHeight == lastHeight {
          print("currHeight == lastHeight")
        } else if currHeight > lastHeight {
          append(currHeight)
        } else { // currHeight < lastHeight
          // Keep popping
          stack.popLast()
          var found = false
          while !stack.isEmpty {
            let lastAppendedHeight = stack.last!
            
            if lastAppendedHeight == currHeight {
              print("lastAppendedHeight == currHeight == \(currHeight)")
              lastHeight = currHeight
              found = true
              break
            } else if lastAppendedHeight < currHeight {
              print("break")
              break
            }
            print("popLast")
            stack.popLast()
          }
          if !found {
            append(currHeight)
          }
        }
        
      }
      
      i += 1
    }
    
    return nBlocks
  }

  var H = [8,8,5,7,9,8,7,4,8]
  H = [1,2,3,4,5]
  H = [1,1,1,1,1,1,1,1,1]
  H = [1,2,3,3,3,2,2,2,2,2,1]
  H = [5,4,3,2,1]
  H = [1,2,1,2,1,2]

  solution1(&H)