Given an unsorted array of nonnegative integers, find a continuous subarray which adds to a given number.

SubArrayCountProblem.swift

import UIKit
import PlaygroundSupport

func findSubArrayWhoseCountMatches(targetValue: Int, in array: [Int]) -> [Int] {
  var sum = 0
  var startIndex = 0
  for index in 0..<array.count {
    sum = sum + array[index]

    while sum > target {
      sum = sum - array[startIndex]
      startIndex = startIndex + 1
    }
    
    if sum == target {
      return [startIndex, index]
    }
  }
  return []
}

let arr = [1, 4, 20, 3, 10, 5]
let target = 33
let subArrayIndexes = findSubArrayWhoseCountMatches(targetValue: target, in: arr)
print(subArrayIndexes)