5b

five.py

@@ -4,7 +4,6 @@ from useful import *
 
 seedstr, rest = headerfooter(open(0))
 seeds = numbers(seedstr)
-ic(seeds)
 
 def getmap(l):
     """
@@ -16,12 +15,11 @@ def getmap(l):
     return source, (dest, list(trips))
 
 guide = {k: v for (k, v) in (getmap(p) for p in pgphs(rest))} # ugh
-ic(guide['water'])
 
 def move(origin, kart):
     for dst, src, size in kart:
         if src <= origin < src + size:
-            return origin + dst - src # i bet part 2 will change this
+            return origin + dst - src
     return origin
 
 def ship(element, target, origin): # ship('seed', 'light', 42)
@@ -30,4 +28,43 @@ def ship(element, target, origin): # ship('seed', 'light', 42)
     dest, kart = guide[element]
     return ship(dest, target, move(origin, kart))
 
+def chop(origin, kart):
+    bego, leno = origin
+    endo = bego + leno
+    if not leno:
+        return []
+    if not kart:
+        return origin,
+    dst, src, size = kart[0]
+    """
+    how generically can we do this?
+    well, when we chop the thing, there's at most going to be
+        - something < dst
+        - something inside dst (to be transformed)
+        - something >= dst+size
+    simply grab these three chunks, and recurse on the first and last.
+    (something already transformed obviously shouldn't be transformed back)
+    """
+    before = (bego, min(endo, src)) if bego < src else (0, 0)
+    after = (max(bego, src+size), endo) if src + size < endo else (0, 0)
+    inside = (max(bego, src), min(endo, src+size)) if not endo <= src or bego >= src+size else (0, 0)
+    during = inside if inside[1] > inside[0] else (0, 0)
+    bl = before[0], before[1]-before[0]
+    dl = during[0]+dst-src, during[1]-during[0]
+    al = after[0], after[1]-after[0]
+    return (a for a in (*chop(bl, kart[1:]),
+            dl,
+            *chop(al, kart[1:])) if a[0] >= 0 and a[1] > 0)
+
+def twoship(element, target, origin, indent=0): # ship('seed', 'light', (420, 69))
+    if len(sys.argv) > 1 and sys.argv[1] == '-v':
+        print(' ' * indent, element, origin)
+    if element == target:
+        return origin
+    dest, kart = guide[element]
+    bis = [twoship(dest, target, c, indent+1) for c in chop(origin, kart)]
+    return bis
+
 print(min(ship('seed', 'location', s) for s in seeds))
+print(min(beg for (beg, sz) in batched(
+    collapse([twoship('seed', 'location', p) for p in batched(seeds, 2)]), 2)))

useful.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 from functools import cache, reduce
-from itertools import permutations, product, combinations, pairwise, groupby, takewhile
-from more_itertools import batched, sliding_window
+from itertools import chain, permutations, product, combinations, pairwise, groupby, takewhile
+from more_itertools import batched, collapse, sliding_window
 from collections import defaultdict, deque
 import re, sys
 import math