[Python] Challenge 4 (Unreviewed) (YearOfProgramming#358)

* challenge 4 in python

* Added a function to make a tree 4 levels deep

challenge_4/python/sarcodian/README.md

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+So I took this out and after a nice long slack discussion, decided to put it back, 
+since what I lacked most was documentation, which was causing a missunderstanding.
+
+So, instead of building a Node class, and recursing my way down, I built each node in 
+list notation using the format tree = [head, [left, [], []], [right, [], []]]
+
+The empty lists are equvalent to None
+
+If you want to add left.left, you simply add tree[1][1] = [left.left, [], []]
+If you want to add left.right, you can add tree[1][2] = [left.right, [], []]
+Same notation if you want to retrieve a node or branch.
+
+TL:DR; I did not hard code a list and reverse it. You can build and manipulate the tree from
+scratch and the reverse fuction will recurse down until the null values and flip them for you.

challenge_4/python/sarcodian/src/challenge_4.py

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+"""
+Each root has two subtrees, each subtree may have a root
+Each tree has the format ['parent',
+                          ['child1',
+                           ['child1.1'],['child1.2']],
+                          ['child2',
+                           ['child2.1'],['child2.2']]]
+"""
+
+import itertools
+
+def reverse(tree):
+    subtree = tree.copy()
+    if len(subtree[1]) < 2 and len(subtree[2]) < 2:
+        return [subtree[0], subtree[2], subtree[1]]
+    elif len(subtree[1]) < 2:
+        return [subtree[0], [reverse(subtree[2])], subtree[1]]
+    elif len(subtree[2]) < 2:
+        return [subtree[0], subtree[2], [reverse(subtree[1])]]
+    else:
+        return [subtree[0], reverse(subtree[2]), reverse(subtree[1])]
+
+
+test = [4,
+        [2,
+         [1], [3]],
+        [7,
+         [6], [9]]
+       ]
+
+def create_large_tree():
+    """
+    Create a tree with up to 4 levels of nodes to show that implementation scales, enter less then 15
+    """
+    value_of_nodes = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 'a', 'b', 'c', 'd', 'e']
+    tree = ''
+    depth = 0
+    count = 0
+
+    while depth < 4:
+        if depth == 0:
+            tree = [value_of_nodes[0], [], []]
+            depth += 1
+            count += 1
+        elif depth == 1:
+            for i in [1,2]:
+                tree[i] = [value_of_nodes[count], [], []]
+                count += 1
+            depth += 1
+        elif depth == 2:
+            for i,j in itertools.product([1,2], repeat=depth):
+                tree[i][j] = [value_of_nodes[count], [], []]
+                count += 1
+            depth += 1
+        elif depth == 3:
+            for i, j, k in itertools.product([1,2], repeat=depth):
+                tree[i][j][k] = [value_of_nodes[count], [], []]
+                count += 1
+            depth += 1
+    return tree
+
+
+print(test)
+test_rev = reverse(test)
+print(test_rev)
+print(reverse(test_rev))
+
+test2 = create_large_tree()
+print(test2)
+test_rev2 = reverse(test2)
+print(test_rev2)
+print(reverse(test_rev2))