number_of_sweets_sum.py

import time


def number_of_sweets(days):
    """
 This function assumes the parameter, days, contains a list of integers in ascending order.   
    
 optimised function where the
 sum_of_sweets counts every odd number and keeps track of the previous calculation.
 This function more clearly displays its efficiency for very long lists.
 
 For explanation we look a list of length 3:
   if days = [3, 5, 9], we first calculate 3,
   sum_of_sweets counts from 1 to 3 and skips every 2nd number
   so, sum_of_sweets(1) = 1 + 3 = 4

   then we calculate 5,
   but we already know the sum_of_sweets from 1 to 3 (which is 4)
   therefore, sum_of_sweets counts from 3 to 5 and adds it to the previous calculation
   so, sum_of_sweets(2) = sum_of_sweets(1) + 5 = 9

   then we calculate 9,
   but we already know the sum_of_sweets from 1 to 5 (which is 9)
   therefore, sum_of_sweets counts from 5 to 9 and adds it to the previous calculation
   so, sum_of_sweets = sum_of_Sweets(2) + 7 + 9 = 25

   in comparison, the original solution computed 3 by looping from 1 each time.
   for example,
       sum_of_sweets = 1 + 3 = 4
       then 5 by,
       sum_of_sweets = 1 + 3 + 5 = 9
       then 9 by,
       sum_of_sweets = 1 + 3 + 5 + 7 + 9 = 25

 """
    min_day = 1
    sum_of_sweets = 0
    for day in range(len(days)):
        while min_day < days[day] + 1:
            sum_of_sweets += min_day
            min_day += 2
        print(sum_of_sweets)
# end of number_of_sweets


# function submitted in hacker rank test
# (equivalent to java code)
def number_of_sweets_submitted(arr):
    for days in range(len(arr)):
        sum = 0
        for day in range(arr[days] + 1):
            if (day % 2 != 0):
                sum += day
        print(sum)
# end of number_of_sweets_submitted


# List of days in a year, where each element i
# is the number of days.
#   For example,
#   i = 2, 2 days have past
#   i = 5, 5 days have past
day_in_year_list = [1, 2, 5, 10000000]

# We pass the above list into the submitted function
# We also time it to compare with the new function.
# The original function give a time of ~ 1.0 second
# for day_in_year_list (length 4)
t1 = time.time()
number_of_sweets_submitted(day_in_year_list)
t2 = time.time()

# We pass the above list into the optimised function
# We also time it to compare with the old function.
# The optimised function gives a time of ~ 0.60
# for day_in_year_list (length 4)

# Therefore, the optimised functions takes about
# half of the time as the the submitted solution.
t3 = time.time()
number_of_sweets(day_in_year_list)
t4 = time.time()

print("The submitted function takes: " + str(t2-t1))
print("The optimised functions takes: " + str(t4-t3))