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y2023/p05.py

@@ -3,33 +3,35 @@ import pathlib
 import re
 
 
-text = open(0).read()
-[seed], *groups = [[[int(n) for n in ln.split()] for ln in group.split(':')[1].strip().splitlines()] for group in text.split('\n\n')]
+def forward(n, groups):
+    for group in groups:
+        for b, a, c in group:
+            if a <= n < a + c:
+                n = n + (b - a)
+                break
+    return n
 
 
-def forward(n):
-    for group in groups:
-        n = next((n + (b - a) for b, a, c in group if a <= n < a + c), n)
+def backward(n, groups):
+    for group in reversed(groups):
+        for b, a, c in group:
+            if b <= n < b + c:
+                n = n - (b - a)
+                break
     return n
 
 
-ans1 = min([forward(n) for n in seed])
+text = open(0).read()
+to_matrix = lambda string: [[int(n) for n in ln.split()] for ln in string.splitlines()]
+[seed], *groups = [to_matrix(string.split(':')[1].strip()) for string in text.split('\n\n')]
+
+ans1 = min([forward(n, groups) for n in seed])
 print(ans1)
 
 ns = []
+pairs = [(a, a + b) for a, b in zip(seed[::2], seed[1::2])]
 for group in reversed(groups):
     ns += [n for b, a, c in group for n in [b, b + c - 1]]
-    ns = [next((n - (b - a) for b, a, c in group if b <= n < b + c), n) for n in ns]
-ans2 = min(forward(n) for n in ns if any(a <= n < a + b for a, b in zip(seed[::2], seed[1::2])))
+    ns = [backward(n, [group]) for n in ns]
+ans2 = min(forward(n, groups) for n in ns if any(a <= n < b for a, b in pairs))
 print(ans2)
-
-
-# old method, slow
-def backward(n):
-    for group in groups[::-1]:
-        n = next((n - (b - a) for b, a, c in group if b <= n < b + c), n)
-    return n
-
-
-pairs = [(a, a + b) for a, b in zip(seed[::2], seed[1::2])]
-next(n for n in itertools.count(ans2) if any(a <= backward(n) < b for a, b in pairs))

y2023/p09.py

@@ -0,0 +1,12 @@
+def historicize(ns):
+    tails = [ns[-1]]
+    while len(set(ns)) > 1:
+        ns = [b - a for a, b in zip(ns, ns[1:])]
+        tails.append(ns[-1])
+    return sum(tails)
+
+
+text = open(0).read()
+data = [[int(n) for n in line.split()] for line in text.splitlines()]
+print(sum(historicize(ns) for ns in data))
+print(sum(historicize(ns[::-1]) for ns in data))