Numbers.scala

package algrithsm

import annotation.tailrec

/**
 * User: flower
 * Date: 11-1-18
 * Time: 下午6:22
 * Description: 
 */

object Numbers {

  import java.lang.Math.max

  def maxSum(arr: List[Int]): Int = {

    var maxNumber = arr(0)

    @tailrec
    def maxSumOfArray(numbers: List[Int], maxEnd: Int, maxSum: Int): Int = numbers match {
      case (x :: xs) =>
        maxNumber = max(x,maxNumber)
        val end = max(maxEnd + x, 0)
        maxSumOfArray(xs, end, max(end, maxSum))
      case _ => maxSum
    }

    val result = maxSumOfArray(arr, 0, 0)

    if(result == 0)
      maxNumber
    else
      result

  }



  def main(args: Array[String]) {
    Console println maxSum(-2 :: -1 :: -3 :: -1 :: Nil)
  }

}