update 2024.12.04 14:54

2024/day04a.py

@@ -0,0 +1,44 @@
+word_search = []
+with open('/home/bandeira/git.bandeira/aoc/2024/day04/input.day04', 'r') as f:
+    for line in f.readlines():
+        word_search.append(list(line.strip()))
+n = len(word_search)
+
+def is_inbounds(i, j):
+    return 0 <= i < n and 0 <= j < n
+
+# part 1
+result = 0
+for i in range(n):
+    for j in range(n):
+        if word_search[i][j] != 'X':
+            continue
+        for di in [-1, 0, 1]:
+            for dj in [-1, 0, 1]:
+                if (di, dj) == (0, 0):
+                    continue
+                if is_inbounds(i+3*di, j+3*dj):
+                    if ''.join(word_search[i+k*di][j+k*dj] for k in range(4)) == 'XMAS':
+                        result += 1
+print(result)
+
+# part 2
+result = 0
+for i in range(n):
+    for j in range(n):
+        if word_search[i][j] != 'A':
+            continue
+        if not is_inbounds(i+1, j+1):
+            continue
+        if not is_inbounds(i+1, j-1):
+            continue
+        if not is_inbounds(i-1, j+1):
+            continue
+        if not is_inbounds(i-1, j-1):
+            continue
+        if not (word_search[i-1][j-1], word_search[i+1][j+1]) in (('M', 'S'), ('S', 'M')):
+            continue
+        if not (word_search[i+1][j-1], word_search[i-1][j+1]) in (('M', 'S'), ('S', 'M')):
+            continue
+        result += 1
+print(result)