day 2 refactor

day02/input

@@ -0,0 +1 @@
+2558912-2663749,1-19,72-85,82984-100358,86-113,193276-237687,51-69,779543-880789,13004-15184,2768-3285,4002-4783,7702278-7841488,7025-8936,5858546565-5858614010,5117615-5149981,4919-5802,411-466,126397-148071,726807-764287,7454079517-7454227234,48548-61680,67606500-67729214,9096-10574,9999972289-10000034826,431250-455032,907442-983179,528410-680303,99990245-100008960,266408-302255,146086945-146212652,9231222-9271517,32295166-32343823,32138-36484,4747426142-4747537765,525-652,333117-414840,13413537-13521859,1626-1972,49829276-50002273,69302-80371,8764571787-8764598967,5552410836-5552545325,660-782,859-1056

day02/sample

@@ -0,0 +1 @@
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124

day02/sol.py

@@ -0,0 +1,65 @@
+def parse(s):
+    ret = []
+    for pair in s.split(','):
+        x,y = pair.split('-')
+        ret.append((int(x),int(y)))
+    return ret
+
+def solve(input):
+    with open(input) as f:
+        ranges = parse(f.read())
+
+    t = 0
+    for lo,hi in ranges:
+        invalid = list(findinvalid(lo,hi,1))
+        #if len(invalid) == 0:
+        #    print(lo,hi,invalid)
+        t += sum(invalid)
+    print(t)
+
+    t2 = 0
+    for lo,hi in ranges:
+        invalid2 = set(findinvalid(lo,hi,2))
+        t2 += sum(invalid2)
+    print(t2)
+
+def findinvalid(lo, hi, part):
+    assert lo <= hi
+    if log10(hi) != log10(lo):
+        assert log10(hi) - log10(lo) == 1
+        yield from findinvalid(lo,exp10(log10(lo))-1, part)
+        yield from findinvalid(exp10(log10(hi)-1),hi, part)
+    elif part == 1:
+        N = log10(hi)
+        if N % 2 == 0:
+            d = N // 2
+            yield from _find(lo,hi,d,N)
+    elif part == 2:
+        N = log10(hi)
+        for d in range(1,N):
+            if N%d == 0:
+                yield from _find(lo,hi,d,N)
+
+def _find(lo, hi, d, N):
+    B = exp10(d)
+    BB = exp10(N-d)
+    factor = sum(exp10(k) for k in range(0,N,d))
+    for i in range(lo//BB, hi//BB+1):
+        if i < B//10:
+            continue
+        if i >= B:
+            break
+        id = i*factor
+        if lo <= id <= hi:
+            #assert(str(i)*(N//d) == str(id)), (i,id)
+            #print(lo, hi, i,B,id)
+            yield id
+
+def exp10(n):
+    return 10 ** n
+
+def log10(n):
+    return len(str(n))
+
+solve("sample")
+solve("input")