get rid of all warnings

challenges/backpack_problem.rst

@@ -0,0 +1,58 @@
+Backpack Problem
+================
+
+**🎯 Optimize the value of a heist.**
+
+.. figure:: burglar.png
+   :alt: Burglar
+
+
+A burglar broke into a villa. There he finds so many valuables that he
+can’t put them all in his backpack. Write a program that makes an
+optimal selection.
+
+The burglar is an experienced professional who can estimate the market
+value and size of each item in no time:
+
+================ ==== ======
+item             size value
+================ ==== ======
+laptop           2    600,-
+cutlery          2    400,-
+spotify speakers 3    300,-
+jewels           2    1100,-
+vase             5    700,-
+camera           2    500,-
+painting         4    900,-
+cash             1    800,-
+================ ==== ======
+
+The backpack has a capacity of ``8``.
+
+When your program manages to pack items worth ``3000``, it can be used
+as an app for amateur burglars.
+
+Hints
+-----
+
+-  the optimal solution uses **dynamic programming**.
+
+Use the following pseudocode:
+
+1.  create an empty list that will include the best combination(s) of
+    items for each backpack size
+2.  insert an empty combination for a size 0 backpack
+3.  start with a size 1 backpack
+4.  copy the best combination for the current size from the previous
+    size, store it as ``current best``
+5.  go through all objects
+6.  create a new combination usign an item plus the best combination for
+    the space remaining
+7.  if the combination is more valuable than the ``current best``,
+    replace ``current best`` by the new combination
+8.  if the combination is worth the same amount, save both
+9.  increase the size of the backpack by 1
+10. repeat step 4 until you reach the desired size
+11. print the best combination for the desired size
+
+*Translated with* `www.DeepL.com <https://www.DeepL.com/Translator>`__

challenges/binary_search.rst

@@ -72,7 +72,7 @@ only one extra recursion is necessary.
 Visual Explanation
 ------------------
 
-.. figure:: .binary-search.png
+.. figure:: binary-search.png
    :alt: BINÄRY SEARCH
 
 *source: idea-instructions.com, CC-BY-NC-SA 4.0*

challenges/blockchain.rst

@@ -0,0 +1,80 @@
+Blockchain
+==========
+
+**🎯 Implement your own blockchain algorithm.**
+
+Step 1
+------
+
+Write a function that generates random transactions in the format
+``(name1, name2, amount)``.
+
+We want to save these transactions *forgery-proof*, so that they are as
+difficult to manipulate as possible afterwards.
+
+Step 2
+------
+
+Define a data type *"Block"* that contains the following:
+
+-  The hash of a previous block
+-  Some transactions
+-  A checksum (any number or string)
+
+Step 3
+------
+
+Write a function that calculates a hash from all properties of a block.
+To do this, represent the entire block as a string. Use the hash
+function ``sha256``:
+
+::
+
+   import hashlib
+
+   h = hashlib.sha256()
+   h.update(text.encode())
+   print(h.hexdigest())
+
+Step 4
+------
+
+Create the blockchain as an empty list.
+
+Create the first block, the "Genesis block". Use ‘genesis’ as previous
+hash. Place some random transactions in the block.
+
+Find a checksum so that the *sha256-hexdigest* ends with four zeros
+(``0000``). You may need to try many checksums.
+
+Add the finished block to the blockchain.
+
+Step 5
+------
+
+Create the second block:
+
+-  The hash is the ``hexdigest`` of the previous block
+-  Add more transactions.
+-  Again find a checksum that generates a ``hexdigest`` with four zeros
+   at the end.
+-  Add the finished block to the blockchain.
+
+Step 6
+------
+
+Generate more blocks.
+
+Questions
+---------
+
+-  What happens if the number of necessary zeros in the hex digest is
+   set to 2 or 6?
+-  What happens if someone changes a transaction in the Genesis block?
+-  What makes the blockchain forgery-proof?
+-  How could a blockchain still be forged?
+-  Why is finding the checksum also called *"proof of work"*?
+-  Why are several computers involved in a blockchain?
+-  What is a *"consensus algorithm"*?
+
+*Translated with* `www.DeepL.com <https://www.DeepL.com/Translator>`__

challenges/dice/dice.rst

@@ -27,4 +27,4 @@ Hints
    :alt: dice faces
 
 
-*Translated with*\ `www.DeepL.com <https://www.DeepL.com/Translator>`__
+*Translated with* `www.DeepL.com <https://www.DeepL.com/Translator>`__

challenges/magic_square.rst

@@ -0,0 +1,29 @@
+Magic Square
+============
+
+**🎯 Solve a magic square.**
+
+-  create a magic square with 3 \* 3 fields.
+-  fill the square with the numbers from 1-9
+-  the sum of the numbers in each row, column and diagonal shall be 15
+-  use each number only once
+-  print the finished square
+
+Hints
+-----
+
+-  Write a function that calculates all sums
+-  A *brute-force* approach is to try out all permutations\*
+-  See the ``itertools`` module
+
+Extra Challenge
+---------------
+
+Fill a magic square with 4 \* 4 fields with the numbers 1-16 (sum 34).
+
+If you don’t want to try all the possibilities (9!), you can describe
+the magic square as a linear system of equations. The Python package
+**PuLP** allows you to express the necessary equations in a very compact
+way.
+
+*Translated with* `www.DeepL.com <https://www.DeepL.com/Translator>`__