21-1

2024/21/21-1.py

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+import re
+
+def makeKeypad(rows):
+    coords = {}
+    gap = '0,0' if len(rows) == 2 else '3,0'
+
+    for i, row in enumerate(rows):
+        for j, key in enumerate(row):
+            if key == ' ':
+                continue
+
+            coords[key] = (i,j)
+
+    return (coords, gap)
+
+# using a networkx graph for shortest paths between numbers worked well in theory
+# but unfortunately led to some issues due to how many corners appeared.
+# for example, 3 to 7 could be done by <<^^, but could also be <^<^, which has
+# extra movements for the second robot and onwards.
+def moveToKey(fromKey, toKey, keypad):
+    coords, keypadGap = keypad
+
+    [r1, c1] = coords[fromKey]
+    [r2, c2] = coords[toKey]
+
+    rowDifference = r2 - r1
+    upDown = ('v' if r2 > r1 else '^') * abs(rowDifference)
+
+    colDifference = c2 - c1
+    leftRight = ('>' if c2 > c1 else '<') * abs(colDifference)
+
+    if (c2 > c1 and f'{r2},{c1}' != keypadGap):
+        return f'{upDown}{leftRight}A'
+
+    if (f'{r1},{c2}' != keypadGap):
+        return f'{leftRight}{upDown}A'
+
+    return f'{upDown}{leftRight}A'
+
+arrowKeypadsNeeded = 2
+total = 0
+with open('2024/21/input.txt') as f:
+    for line in f:
+        line = line.strip()
+        numericPart = int(re.search(r'(\d+)', line).group(0))
+
+
+        # first arrow keypad robot's steps
+        numpadKeys = makeKeypad(["789", "456", "123", " 0A"])
+        previous = 'A'
+        path = ''
+        for i, char in enumerate(line):
+            path += moveToKey(previous, char, numpadKeys)
+            previous = char
+        print (path)
+
+        # second through to last arrow pad robot's codes
+        arrowKeys = makeKeypad([' ^A', '<v>'])
+        previous = 'A'
+        for _ in range(arrowKeypadsNeeded):
+            newPath = ''
+            for i, char in enumerate(path):
+                newPath += moveToKey(previous, char, arrowKeys)
+                previous = char
+            print (newPath)
+            path = newPath
+
+        totalInputs = len(path)
+        print('total inputs:', totalInputs)
+
+        complexity = totalInputs * numericPart
+        print(f'{line}: {totalInputs} * {numericPart} = {complexity}')
+
+        total += complexity
+
+    print(total)
+
+

2024/21/testinput.txt

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+029A
+980A
+179A
+456A
+379A