class Solution:
  def search(self, arr, target_sum):
    # TODO: Write your code here
    l, r = 0, len(arr) - 1

    while l<r:
      curr= arr[l] + arr[r]
      if curr>target_sum:
        r-=1
      elif curr<target_sum:
        l+=1
      else:
        return [l,r]
    return [-1, -1]