day 19 part 2

day19/sol2.py

@@ -0,0 +1,31 @@
+from functools import cache
+def solve(file):
+    designs = file.readline().strip().split(", ")
+    assert file.readline() == '\n'
+
+    ds = set(designs)
+
+    @cache
+    def ways(x):
+        n = 0
+        if x in ds:
+            n += 1
+        if len(x) > 1:
+            for i in range(1,len(x)):
+                if x[:i] in ds:
+                    n += ways(x[i:])
+        #print("ways(%s) = %s"%(x,n))
+        return n
+
+    t = 0
+    for line in file:
+        towel = line.strip()
+        w = ways(towel)
+        #print(w, towel)
+        t += w
+
+    print(t)
+        
+
+solve(open('sample1.in'))
+solve(open('input'))