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day 2 refactor

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magical 2025-12-02 08:06:03 +00:00
parent a0ff488cf1
commit 94ccfd4e18
1 changed files with 38 additions and 44 deletions
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60
day02/sol.py
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@ -11,7 +11,7 @@ def solve(input):
t = 0
for lo,hi in ranges:
invalid = list(findinvalid(lo,hi))
invalid = list(findinvalid(lo,hi,1))
#if len(invalid) == 0:
# print(lo,hi,invalid)
t += sum(invalid)
@ -19,53 +19,47 @@ def solve(input):
t2 = 0
for lo,hi in ranges:
invalid2 = set(findinvalid2(lo,hi))
invalid2 = set(findinvalid(lo,hi,2))
t2 += sum(invalid2)
print(t2)
def findinvalid(lo, hi):
assert len(str(hi)) - len(str(lo)) <= 1
def findinvalid(lo, hi, part):
assert lo <= hi
j = len(str(lo)) // 2
if j < 1:
# (1,19) => [11]
j = 1
for B in [10**j, 10**(j+1)]:
for i in range(lo//B, hi//B+1):
if i < B//10:
continue
if i >= B:
break
id = i*B + i
if lo <= id <= hi:
assert(str(i)+str(i) == str(id)), (i,id)
#print(lo, hi, i,B,id)
yield id
def findinvalid2(lo, hi):
assert lo <= hi,(lo,hi)
if len(str(hi)) != len(str(lo)):
assert len(str(hi)) - len(str(lo)) == 1
yield from findinvalid2(lo,10**len(str(lo))-1)
yield from findinvalid2(10**(len(str(hi))-1),hi)
return
N = len(str(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:
B = 10**d
BB = 10**(N-d)
factor = sum(10**k for k in range(0,N,d))
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
#print(lo,hi,factor,i,id)
if lo <= id <= hi:
#assert(str(i)*(N//d) == str(id)), (i,id)
#print(lo, hi, i,B,id)
yield id
#solve("sample")
def exp10(n):
return 10 ** n
def log10(n):
return len(str(n))
solve("sample")
solve("input")