export function sumMinWindow(numbers: number[], k: number): number {
  if (numbers.length < k) return -1

  let windowSum: number = 0
  // Updates windowSum with the first window of size k
  for (let i = 0; i < k; i++) {
    windowSum += numbers[i]
  }

  let minSum = windowSum
  // Slides the window across the array updating current window sum
  for (let i = k; i < numbers.length; i++) {
    windowSum += numbers[i] - numbers[i - k]
    minSum = Math.min(minSum, windowSum)
  }  

  return minSum;
}