Day 5 solution works, day 4 doesn't

2024/day04.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+
+with open("./2024/inputs/day04.txt") as f:
+    puzzle = [l.strip() for l in f.readlines()]
+
+maxY = len(puzzle) - 1
+maxX = len(puzzle[0]) - 1
+
+def possible_words(p, start):
+    y = start[0]
+    x = start[1]
+    ret = []
+
+    # get the two possible horizontal matches
+    # skip them if x - 3 < 0 (word would be truncated on the left)
+    # or x + 3 > maxX (word would be truncated on the right)
+    if not ((x + 3) > maxX):
+        ret.append(str(f"{p[y][x]}{p[y][x + 1]}{p[y][x + 2]}{p[y][x + 3]}"))
+    
+    if not ((x - 3) < 0):
+        ret.append(str(f"{p[y][x]}{p[y][x - 1]}{p[y][x - 2]}{p[y][x - 3]}"))
+    
+    # get the two possible vertical matches
+    # skip them if y - 3 < 0 (word would be truncated on the top)
+    # or y + 3 > maxY (word would be truncated on the bottom)
+    if not ((y + 3) > maxY):
+        ret.append(str(f"{p[y][x]}{p[y + 1][x]}{p[y + 2][x]}{p[y + 3][x]}"))
+    
+    if not ((y - 3) < 0):
+        ret.append(str(f"{p[y][x]}{p[y - 1][x]}{p[y - 2][x]}{p[y - 3][x]}"))
+    
+    # get the four diagonals, again with some (basic) bounds checking
+    if not ((y + 3) > maxY) and not ((x + 3) > maxX):
+        ret.append(str(f"{p[y][x]}{p[y + 1][x + 1]}{p[y + 2][x + 2]}{p[y + 3][x + 3]}"))
+    
+    if not ((y - 3) < 0) and not ((x - 3) < 0):
+        ret.append(str(f"{p[y][x]}{p[y - 1][x - 1]}{p[y - 2][x - 2]}{p[y - 3][x - 3]}"))
+    
+    if not ((y + 3) > maxY) and not ((x - 3) < 0):
+        ret.append(str(f"{p[y][x]}{p[y + 1][x - 1]}{p[y + 2][x - 2]}{p[y + 3][x - 3]}"))
+    
+    if not ((y - 3) < 0) and not ((x + 3) > maxX):
+        ret.append(str(f"{p[y][x]}{p[y - 1][x + 1]}{p[y - 2][x + 2]}{p[y - 3][x + 3]}"))
+    
+    return ret
+
+xmas_count = 0
+for y in range(maxY):
+    for x in range(maxX):
+        if puzzle[y][x] == "X":
+            words = possible_words(puzzle, (y, x))
+            for word in words:
+                xmas_count += word.count("XMAS")
+    
+        if puzzle[y][x] == "S":
+            words = possible_words(puzzle, (y, x))
+            for word in words:
+                xmas_count += word.count("SAMX")
+
+print(xmas_count)

2024/day05.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+
+def is_valid_update(update, order_reqs):
+    valid_update = True
+    for i in range(0, len(update)):
+        if update[i] in order_reqs:
+            for j in range(0, len(update)):
+                if update[j] in order_reqs[update[i]] and j < i:
+                    valid_update = False
+    
+    return valid_update
+
+def fix_update(update, order_reqs):
+    if is_valid_update(update, order_reqs):
+        return update
+    else:
+        fixed_update = update
+        for i in range(0, len(update)):
+            if update[i] in order_reqs:
+                for j in range(0, len(update)):
+                    if update[j] in order_reqs[update[i]] and j < i:
+                        fixed_update[i], fixed_update[j] = fixed_update[j], fixed_update[i]
+                        if is_valid_update(fixed_update, order_reqs):
+                            return fixed_update
+                        else:
+                            return fix_update(fixed_update, order_reqs)
+
+with open("./2024/inputs/day05.txt") as f:
+    lines = [l.strip() for l in f.readlines()]
+
+order_reqs = {}
+updates = []
+nums_ended = False
+
+for l in lines:
+    if l == "":
+        nums_ended = True
+        continue
+
+    if not nums_ended:
+        before, after = [int(n) for n in l.split("|")]
+        if before not in order_reqs:
+            order_reqs[before] = [after]
+        else:
+            order_reqs[before].append(after)
+
+    else:
+        updates.append([int(n) for n in l.split(",")])
+
+middle_total = 0
+invalid_updates = []
+for update in updates:
+    if is_valid_update(update, order_reqs):
+        middle_total += update[int((len(update) - 1) / 2)]
+    else:
+        invalid_updates.append(update)
+
+print(middle_total)
+
+middle_total_fixed = 0
+for update in invalid_updates:
+    fixed_update = fix_update(update, order_reqs)
+    middle_total_fixed += fixed_update[int((len(fixed_update) - 1) / 2)]
+
+print(middle_total_fixed)

2024/inputs/day04.txt

@@ -0,0 +1,10 @@
+....XXMAS.
+.SAMXMS...
+...S..A...
+..A.A.MS.X
+XMASAMX.MM
+X.....XA.A
+S.S.S.S.SS
+.A.A.A.A.A
+..M.M.M.MM
+.X.X.XMASX