The level of palindrome (Editorial)

Written by Mudae_Wasabi

The problem begins by asking us to input a number, which we store in the variable m:

m = input()

Next, we are told that if this number is not a palindrome, we need to reverse its digits and add the reversed number to the original number.

In other words, we keep reversing the digits of m and adding it to m until the number becomes a palindrome. The number of reversing operations will be called the 'palindromicity degree' of the number.

Initially, the number of operations is set to 0:

i = 0

To stop the process when the number m becomes a palindrome, we use the following loop condition:

while str(m) != str(m)[::-1]:

Here, str(m)[::-1] reverses the digits of the number m. For example, if m is 785, str(m)[::-1] becomes 587.

The != operator means "not equal to". So, the loop runs as long as m is not equal to its reverse. If m is 5, for example, the code would check if a == 5 and only execute the block if a is exactly 5. The != condition works in reverse—executing the block when the number doesn't match.

Now, we create a new variable a to hold the reverse of m:

a = int(str(m)[::-1])

Note: We use int() to convert the reversed string back into an integer, since we can't perform addition with strings.

Then, we update m by adding the original number to the reversed number:

m = int(m) + a

After each operation, we increment the operation count by 1:

i += 1

Finally, to output the "palindromicity degree," we print the value of i:

print(i)

Here’s how the full code looks:

m = input()
i = 0
while str(m) != str(m)[::-1]:
    a = int(str(m)[::-1])
    m = int(m) + a
    i += 1
print(i)