La Fée Verte @Absinthe@qoto.org

#toyprogrammingchallenge
#python Here's another freebie, I assume it is python specific because they start with a base of python code. But if it makes sense, try it in whatever language you like:

This problem was asked by Google.

Given the root to a binary tree, implement serialize(root), which serializes the tree into a string, and deserialize(s), which deserializes the string back into the tree.

For example, given the following Node class

class Node:
def __init__(self, val, left=None, right=None):
self.val = val
self.left = left
self.right = right
The following test should pass:

node = Node('root', Node('left', Node('left.left')), Node('right'))
assert deserialize(serialize(node)).left.left.val == 'left.left'

#toyprogrammingchallenge
Here's a Freebie!

This problem was asked by Stripe.

Given an array of integers, find the first missing positive integer in linear time and constant space. In other words, find the lowest positive integer that does not exist in the array. The array can contain duplicates and negative numbers as well.

For example, the input [3, 4, -1, 1] should give 2. The input [1, 2, 0] should give 3.

You can modify the input array in-place.

# This problem was asked by Jane Street.
#
# cons(a, b) constructs a pair,
# and car(pair) and cdr(pair) returns the first and last element of that
# pair. For example, car(cons(3, 4)) returns 3, and cdr(cons(3, 4))
# returns 4.
#
# Given this implementation of cons:
#
# def cons(a, b):
# def pair(f):
# return f(a, b)
# return pair
#
# Implement car and cdr

def cons(a, b):
def pair(f):
return f(a, b)
return pair

def car(pair):
def f(a, b):
return a
return pair(f)

def cdr(pair):
def f(a, b):
return b
return pair(f)

print cdr(cons(3,4))
print car(cons(3,4))

#toyprogrammingchallenge

Good morning and here comes the latest challenge.

https://git.qoto.org/Absinthe/onetonine/blob/master/README.md

The numbers 1 2 3 4 5 6 7 8 9 can have either the operator "+" or "-" placed between them.
As well, if no operator is placed, then the adjoining numbers go together such as 1 2 would
become "12" or 1 2 3 would become "123" and so forth.

The goal is to find the combinations that would make the line calculate up to 100 exactly.

Here is an example: 12 + 3 - 4 + 5 + 67 + 8 + 9 = 100

Would like maybe something other than eval().

@zingbretsen care to take a shot at a fix for my one-line solution in this one?

#toyprogrammingchallenge

I found a corner case on the find sum in list that I overlooked. If the list is [1,2,5] and the number is 4 I will return true because I am looking through the whole list for K-element and will of course find element. I was so happy to get a single line that worked, I am wondering if I can fix it and still keep it one line?

https://git.qoto.org/Absinthe/sum-of-number-in-list

I know count may work better than any, or some other logic to handle the special case of K-element == element

#toyprogrammingchallenge

Okay, here is another freebie :) I will put in a real one before the end of the weekend.

Basically, you are given a list from which you need to create a new list where each element is the product of all the "OTHER" elements.

I found a few interesting corner cases.

I challenge you to give it a try!

Read the challenge here:

https://git.qoto.org/Absinthe/productnot/blob/master/README.md

My attempt is checked into that repo as well.

#toyprogrammingchallenge

Here's another freebie!! I signed up for a programming problem of the day. I got my first one today, rated "easy".

Here's the description of the problem.

https://git.qoto.org/Absinthe/sum-of-number-in-list/blob/master/README.md

My code to solve it, though not clean and delicious, is in that same repo, but certainly give it a crack before peeking. :)

#toyprogrammingchallenge

How about a guessing game? Or job interview type programming tasks?

#toyprogrammingchallenge

Okay, I thought I came up with some good challenges and a fun freebie to go with them. I seem to be getting some followers, but not a lot of people trying them.

What kinds of things are you all interested in? I can find all sorts of things, many of them are math-y (statistics and things like that), or string management and still others require you be willing to handle things like differential equations.

If you mention what you might like I can either find some or make some up.