A "cool number" is determined by the following process. Start with the initial integer. Replace this number with the sum of the square of its digits. Repeat this process until the result is 1 (where the sequence remains 1) or it loops endlessly.
For instance, let's take 23 as an example:
1. 2^2 + 3^2 = 13
2. 1^2 + 3^2 = 10
3. 1^2 + 0^2 = 1
Therefore 23 is a "cool number";
HINT: All "uncool numbers" will yield "4" at some point in their sequence then repeat in a loop forever.
Your task: determine the sum of all "cool numbers" starting with 1 and going up to and including 1,000,000.
When you're done, make a POST request to the following APIs:
/code1, /code2, /code3, ..., /code100
with the header "X-COOL-SUM" equal to your answer. Most of the routes will return 404. But some will return a letter when provided with the right "cool sum". The code is the letters put together in the order of the requests.
TIP: I often get messages from frustrated people asking me if there's a bug in this challenge. I never guarantee that any app is 100% bug-free, but many people have been able to complete this challenge. So chances are, if you are struggling, it isn't a bug ;).