day 9, trivial recursion

d09/part1.py

@@ -0,0 +1,11 @@
+import sys
+
+L = [list(map(int,l.split(' '))) for l in sys.stdin.read().splitlines()]
+
+def extrapolate(L):
+    if all(not a for a in L):
+        return L+[0]
+    M = [b-a for a,b in zip(L,L[1:])]
+    return L+[L[-1]+extrapolate(M)[-1]]
+
+print(sum(extrapolate(l)[-1] for l in L))

d09/part2.py

@@ -0,0 +1,11 @@
+import sys
+
+L = [list(map(int,l.split(' '))) for l in sys.stdin.read().splitlines()]
+
+def extrapolate(L):
+    if all(not a for a in L):
+        return [0]+L
+    M = [b-a for a,b in zip(L,L[1:])]
+    return [L[0]-extrapolate(M)[0]]+L
+
+print(sum(extrapolate(l)[0] for l in L))