day 5 part 2

day05/sol2.py

@@ -0,0 +1,92 @@
+def read_map(input):
+    map = []
+    for line in input:
+        if not line.strip():
+            break
+        dst, src, count = nums(line)
+        map.append((dst, src, count))
+    return map
+
+
+def overlap(a,b, x,y):
+    """ if two ranges a..a+b and x..x+y overlap, returns the overlapping range"""
+    if b <= x or y <= a:
+        return (0,0) # no overlap
+    return max(a,x), min(b,y)
+
+def lookup(map, m,n):
+    r = []
+    used = []
+    for dst, src, count in map:
+        a,b = overlap(m,m+n, src,src+count)
+        if a != b:
+            assert a < b
+            used.append((a,b))
+            r.append((a-src+dst,b-a))
+    if not used:
+        r.append((m,n))
+    else:
+        used.sort()
+        end = m+n
+        for a,b in used:
+            assert m <= a
+            if m < a:
+                r.append((m, a-m))
+            m = b
+        if m < end:
+            r.append((m,end-m))
+    return r
+
+def nums(s):
+    return [int(x) for x in s.split()]
+
+def read_puzzle(input):
+    l = next(input)
+    name,_, data = l.partition(": ")
+    assert name == 'seeds'
+    seeds = nums(data)
+
+    maps = {}
+    for l in input:
+        if l.strip():
+            assert ':' in l
+            name = l.split()[0]
+            frm, _, to = name.partition('-to-')
+            assert frm
+            assert to
+            map = read_map(input)
+            maps[(frm,to)] = map
+
+    print(seeds)
+    print(maps)
+
+    locs = []
+    for i in range(0, len(seeds), 2):
+        m,n = seeds[i:i+2]
+        print(n, lookup(maps[('seed','soil')], m,n), seed2loc(maps, m,n))
+        locs.extend(seed2loc(maps, m,n))
+
+    print(min(locs))
+
+
+def seed2loc(maps, m,n):
+    r = [(m,n)]
+    for a,b in [
+        ('seed', 'soil'),
+        ('soil', 'fertilizer'),
+        ('fertilizer', 'water'),
+        ('water', 'light'),
+        ('light', 'temperature'),
+        ('temperature', 'humidity'),
+        ('humidity', 'location'),
+    ]:
+        next = []
+        for m,n in r:
+            s = lookup(maps[a,b], m,n)
+            print(a,b,m,n,":", s)
+            next.extend(s)
+        r = next
+    return r
+
+import sys
+read_puzzle(sys.stdin)