Day04

day04.py

@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+
+#      N
+#   NW   NO
+# W    X    O
+#   SW   SO
+#      S
+
+# 1
+x = list("XMAS")
+
+h = list()
+with open('day04') as f:
+    for l in f:
+        h.append([*l.strip()])
+
+def idx(i,j,k):
+    global h,x
+    if i<0 or j<0 or i>=len(h) or j>=len(h[0]):
+        return False
+    if h[i][j] != x[k]:
+        return False
+    return True
+
+def fmas(i,j):
+    n=o=s=w=1
+    no=so=sw=nw=1
+
+    for k in range(4):
+        if not idx(i,j+k, k): o = 0
+        if not idx(i,j-k, k): w = 0
+        if not idx(i+k,j,k): s = 0
+        if not idx(i-k,j,k): n = 0
+
+        if not idx(i-k,j+k,k): no = 0
+        if not idx(i+k,j-k,k): sw = 0
+        if not idx(i-k,j-k,k): nw = 0
+        if not idx(i+k,j+k,k): so = 0
+
+    return n+o+s+w+no+so+sw+nw
+
+res = 0
+for i in range(len(h)):
+    for j in range(len(h[0])):
+        if h[i][j] == 'X':
+            res += fmas(i,j)
+
+# 2
+def idx2(i,j):
+    global h,x
+    if i<0 or j<0 or i>=len(h) or j>=len(h[0]):
+        return False
+    if h[i][j] == 'S':
+        return 'S'
+    if h[i][j] == 'M':
+        return 'M'
+    return False
+
+def fmas2(i,j):
+    no = idx2(i-1,j+1)
+    sw = idx2(i+1,j-1)
+    nw = idx2(i-1,j-1)
+    so = idx2(i+1,j+1)
+
+    if not no: return 0
+    if not sw: return 0
+    if not nw: return 0
+    if not so: return 0
+
+    if sw == no: return 0
+    if nw == so: return 0
+
+    return 1
+
+
+res2 = 0
+for i in range(len(h)):
+    for j in range(len(h[0])):
+        if h[i][j] == 'A':
+            res2 += fmas2(i,j)