CCT academy task 2023

task_2023.py

"""
My comments
Illumination for every street light is the sum of self illumination (1 if street light is working,
0 if street light is not working), plus illuminations of working neighbouring street lights.

Taking into account only thouse, which illuminations are greater than 0.01, we should use in calculations
only thouse in distance of 180 m or index +/- 9. These illuminations can be calculated using function
below (calculate_illumination() function):
"""

def calculate_illumination(length):
  distance = 0
  n = 0
  illuminations = []
  while distance <= length :
    illumination = 3**(-(distance/90)**2)
    if illumination > 0.01:
      illuminations.append(illumination)
      print(f"{n}: at {distance} meters with {round(illumination, 3)} illumination.")
      distance += 20
      n += 1
    else:
      break
  print(illuminations)
  
calculate_illumination(2000)


def find_index_of_darkest_street_light(road_length: int, not_working_street_lights: list[int]) -> int:
  working_neighbour_illuminations = [1.0,
                                    0.9471929492141141,
                                    0.8049220530197625,
                                    0.613685849032916,
                                    0.41977377692101514,
                                    0.257609226691527,
                                    0.14183533411213797,
                                    0.07006229694981106,
                                    0.031049972484260627,
                                    0.012345679012345678]

  # Making a list of WORKING street lights for calculation check
  working_street_lights = []
  distance = 0
  light_index = 0
  while distance <= road_length:
    if light_index in not_working_street_lights:
      light_index += 1
      distance += 20
    else:
      working_street_lights.append(light_index)
      light_index += 1
      distance += 20
  
  illuminations = [] # illuminations for not working street lights
  below_one_illuminations_index = [] #index of street lights where illumination < 1
  consecutives_below_one = []
  below_one_illuminations = []
  for val in not_working_street_lights:
    illumination = 0 # self illumination of not working street light
    for delta in range(-9, 10):
      calculate_number = val + delta
      if calculate_number in working_street_lights:
        illumination = illumination + working_neighbour_illuminations[abs(delta)]
    illuminations.append(illumination) # append street light illumination to the list
    if illumination < 1:
      below_one_illuminations_index.append(val) # index of very dimm (<1) street light
      below_one_illuminations.append(illumination) # values of very dimm (<1) street light      
  
  # ADDITIONAL TASK section starts here.
  # Logic: At least every 7th street light should be working to have cumulative illumination above 1. We should check if len(below_one_illuminations) > 14 then replace every 7th lamp (remove every 7th member from list and check again), if list length < 14 we can simply remove the midle number. Downsides are that we can have 15 inactive lamps in a row, then some singles or 2-3, hence index consistency check should be implemented.
  # Below code builds the list of consecutives list from non_working and illuminations_below_one (code borrowed from https://softhints.com/find-consecutive-numbers-in-a-list-in-python/, I chose vanilla python version at the end of article.)
  if len(below_one_illuminations) > 14:  
    current_consecutive = [below_one_illuminations_index[0]]
    for i in range(1, len(below_one_illuminations_index)):
      if below_one_illuminations_index[i] == below_one_illuminations_index[i-1] + 1:
          current_consecutive.append(below_one_illuminations_index[i])
      else:
          if len(current_consecutive) > 1:
              consecutives_below_one.append(current_consecutive)
          current_consecutive = [below_one_illuminations_index[i]]
    if len(current_consecutive) > 1:
      consecutives_below_one.append(current_consecutive)
  # END of borrowed code.

  # At least every 7th member of long inactive sequence should be replaced `len(consecutives_below_one[i])/7`, to keep illumination above 1.
  should_be_brightened = []
  for i in range(0, len(consecutives_below_one)):
    if len(consecutives_below_one[i]) > 7:
      j = 3
      while j < len(consecutives_below_one[i]):
        should_be_brightened.append(consecutives_below_one[i][j])
        j = j + 7
  # ADDITIONAL task code segment ENDS here. Outputs via `print()` will be provided below.
  
  dimmest_set = []
  dimmest = illuminations.index(min(illuminations))
  dimmest_set.append(dimmest)
  
  print(f"Lamps on lightposts No. {should_be_brightened} should be changed to keep illumination at least 1.")
  print(f"Total quantity of lamps should be changed to keep illumination at least 1: {len(should_be_brightened)}.")
  print(f"The dimmest lamp for change is No. {not_working_street_lights[dimmest_set[0]]}")
  
  # Row below returns the dimmest lamp post index starting to count from 0 for testing.
  return not_working_street_lights[dimmest_set[0]]

find_index_of_darkest_street_light(road_length=200000, not_working_street_lights=[4, 5, 6, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217])

if __name__ == "__main__":
    # This is an example test. When evaluating the task, more will be added:
    assert find_index_of_darkest_street_light(road_length=200, not_working_street_lights=[4, 5, 6]) == 5
    print("ALL TESTS PASSED")

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