day 4, basic grid processing

d04/part1.py

@@ -0,0 +1,26 @@
+import sys, os
+
+L = sys.stdin.read().strip().split("\n")
+G = [list(l) for l in L]
+H = len(G)
+W = len(G[0])
+
+M4 = [(0,1),(0,-1),(1,0),(-1,0)]
+D4 = [(1,1),(-1,-1),(1,-1),(-1,1)]
+M8 = M4 + D4
+
+S = 0
+for i in range(H):  # rows
+    for j in range(W):  # cols
+        if G[i][j] == "X":
+            for (dx,dy) in M8:
+                xi = i
+                yj = j
+                for l in 'MAS':
+                    xi += dx
+                    yj += dy
+                    if xi<0 or xi>=H or yj<0 or yj>=W or G[xi][yj]!=l:
+                        break
+                else: # if the inner loop wasn't broken.
+                    S += 1
+print(S)

d04/part2.py

@@ -0,0 +1,16 @@
+import sys, os
+
+L = sys.stdin.read().strip().split("\n")
+G = [list(l) for l in L]
+H = len(G)
+W = len(G[0])
+
+S = 0
+for i in range(1,H-1):  # rows
+    for j in range(1, W-1):  # cols
+        if G[i][j] == "A":
+            for P in ["MMSS", "SMMS", "SSMM", "MSSM"]:
+                if G[i-1][j-1] == P[0] and G[i-1][j+1] == P[1] \
+                  and G[i+1][j+1] == P[2] and G[i+1][j-1] == P[3]:
+                    S+=1
+print(S)