Beautiful Days at the Movies : HackerRank Solution in Python

Solution in Python 3

🔗BDAM (github.com)

def beautifulDays(i, j, k):
    beautifulDays = 0
    for day in range(i, j+1):
        rev = int(str(day)[::-1])
        if abs(rev-day)%k==0:
            beautifulDays+=1 
         
    return beautifulDays

Explanation

Firstly we declare a variable called beautifulDays and initialize it to 0.

beautifulDays = 0

Then, we use a for loop and iterate from i i.e the starting the day number to j i.e the ending day number using a variable called day.

for day in range(i, j+1):

Inside the for loop, We first find the reverse of the number, We do so by converting day which is an integer into a string and then by indexing we reverse the string and convert it back to an integer. We store the reverse of day in a variable called rev.

rev = int(str(day)[::-1])

def beautifulDays(i, j, k):
    beautifulDays = 0
    for day in range(i, j+1):
        rev = int(str(day)[::-1])

Then, we use an if block to check if the subtraction of day and rev is evenly divisible by k.

If the modulus of absolute value of (day-rev) and k is equal to 0 then it is a beautiful day and thus we increment beautifulDays by 1.

if abs(rev-day)%k==0:
            beautifulDays+=1

At the end of our program, we return beautifulDays.

return beautifulDays