This was a problem about parsing a large, unknown shape JSON string and finding the sum of all numbers present.
- Using python, a dynamic language made decoding the JSON easy.
- Using basic reflection with
isinstancemade dealing with the different JSON value types easy. - I used a basic recursive solution to go through the entire object. Python doesn't support tail recursion, so if the object was truly huge, my stack would eventually blow up. But it's OK here.
Overall an easy problem that shows the power of python.
2015 Day 12 on AdventOfCode.com
Santa's Accounting-Elves need help balancing the books after a recent order. Unfortunately, their accounting software uses a peculiar storage format. That's where you come in.
They have a JSON document which contains a variety of things: arrays
([1,2,3]), objects ({"a":1, "b":2}), numbers, and strings. Your first job is
to simply find all of the numbers throughout the document and add them
together.
For example:
[1,2,3]and{"a":2,"b":4}both have a sum of 6.[[[3]]]and{"a":{"b":4},"c":-1}both have a sum of 3.{"a":[-1,1]}and[-1,{"a":1}]both have a sum of 0.[]and{}both have a sum of 0.
You will not encounter any strings containing numbers.
What is the sum of all numbers in the document?
Uh oh - the Accounting-Elves have realized that they double-counted everything red.
Ignore any object (and all of its children) which has any property with the value "red". Do this only for objects ({...}), not arrays ([...]).
[1,2,3]still has a sum of 6.[1,{"c":"red","b":2},3]now has a sum of 4, because the middle object is ignored.{"d":"red","e":[1,2,3,4],"f":5}now has a sum of 0, because the entire structure is ignored.[1,"red",5]has a sum of 6, because "red" in an array has no effect.