Rename Project Euler directories and other dependent changes (#3300)

* Rename all Project Euler directories:

Reason:
The change was done to maintain consistency throughout the directory
and to keep all directories in sorted order.

Due to the above change, some config files had to be modified:
'problem_22` -> `problem_022`

* Update scripts to pad zeroes in PE directories

project_euler/problem_018/solution.py

@@ -0,0 +1,64 @@
+"""
+By starting at the top of the triangle below and moving to adjacent numbers on
+the row below, the maximum total from top to bottom is 23.
+
+3
+7 4
+2 4 6
+8 5 9 3
+
+That is, 3 + 7 + 4 + 9 = 23.
+
+Find the maximum total from top to bottom of the triangle below:
+
+75
+95 64
+17 47 82
+18 35 87 10
+20 04 82 47 65
+19 01 23 75 03 34
+88 02 77 73 07 63 67
+99 65 04 28 06 16 70 92
+41 41 26 56 83 40 80 70 33
+41 48 72 33 47 32 37 16 94 29
+53 71 44 65 25 43 91 52 97 51 14
+70 11 33 28 77 73 17 78 39 68 17 57
+91 71 52 38 17 14 91 43 58 50 27 29 48
+63 66 04 68 89 53 67 30 73 16 69 87 40 31
+04 62 98 27 23 09 70 98 73 93 38 53 60 04 23
+"""
+import os
+
+
+def solution():
+    """
+    Finds the maximum total in a triangle as described by the problem statement
+    above.
+
+    >>> solution()
+    1074
+    """
+    script_dir = os.path.dirname(os.path.realpath(__file__))
+    triangle = os.path.join(script_dir, "triangle.txt")
+
+    with open(triangle, "r") as f:
+        triangle = f.readlines()
+
+    a = [[int(y) for y in x.rstrip("\r\n").split(" ")] for x in triangle]
+
+    for i in range(1, len(a)):
+        for j in range(len(a[i])):
+            if j != len(a[i - 1]):
+                number1 = a[i - 1][j]
+            else:
+                number1 = 0
+            if j > 0:
+                number2 = a[i - 1][j - 1]
+            else:
+                number2 = 0
+            a[i][j] += max(number1, number2)
+    return max(a[-1])
+
+
+if __name__ == "__main__":
+    print(solution())