find-low-high-index.py

def find_low_index(arr, key):
  
  low = 0
  high = len(arr) - 1
  mid = int(high / 2)

  while low <= high:

    mid_elem = arr[mid]

    if mid_elem < key:
      low = mid + 1
    else:
      high = mid - 1

    mid = low + int((high - low) / 2)

  if low < len(arr) and arr[low] == key:
    return low

  return -1

def find_high_index(arr, key):
  low = 0
  high = len(arr) - 1
  mid = int(high / 2)

  while low <= high:
    mid_elem = arr[mid]

    if mid_elem <= key:
      low = mid + 1
    else:
      high = mid - 1

    mid = low + int((high - low) / 2);
  
  if high == -1:
    return high

  if high < len(arr) and arr[high] == key:
    return high

  return -1


array = [1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 6, 6]
key = 5
low = find_low_index(array, key)
high = find_high_index(array, key)
print("Low Index of " + str(key) + ": " + str(low))
print("High Index of " + str(key) + ": " + str(high))

key = -2
low = find_low_index(array, key)
high = find_high_index(array, key)
print("Low Index of " + str(key) + ": " + str(low))
print("High Index of " + str(key) + ": " + str(high))