tvl-depot/advent-of-code/day_4.py
William Carroll 5c9079a410 Splice ./universe directory into ./
Manually merging:
- README.md: I added the description from universe/README.md into the heading of
  dotfiles/README.md.
- .envrc: dotfiles/.envrc was a superset of universe/.envrc
- .gitignore: Adding some of the ignored patterns from universe/.gitignore to
  dotfiles/.gitignore

Everything else here should be a simple rename.
2020-01-29 14:43:20 +00:00

35 lines
771 B
Python

import re
start = 134792
end = 675810
def satisfies(x):
x = str(x)
result = False
double, not_decreasing = False, False
# double and *only* double exists
for i in range(len(x) - 1):
# double and left-of-a is BOL or !x
# and right-of-b is EOL or !x
a, b = x[i], x[i + 1]
bol = i - 1 < 0
eol = i + 2 >= len(x)
if a == b and (bol or x[i - 1] != a) and (eol or x[i + 2] != a):
double = True
break
# not_decreasing
prev = int(x[0])
for a in x[1:]:
a = int(a)
if prev > a:
return False
prev = a
not_decreasing = True
return double and not_decreasing
print(len([x for x in range(start, end + 1) if satisfies(x)]))