# --- Day 4: Camp Cleanup ---

# Space needs to be cleared before the last supplies can be unloaded from the
# ships, and so several Elves have been assigned the job of cleaning up
# sections of the camp. Every section has a unique ID number, and each Elf is
# assigned a range of section IDs.

# However, as some of the Elves compare their section assignments with each
# other, they've noticed that many of the assignments overlap. To try to
# quickly find overlaps and reduce duplicated effort, the Elves pair up and
# make a big list of the section assignments for each pair (your puzzle input).

# For example, consider the following list of section assignment pairs:

# 2-4,6-8
# 2-3,4-5
# 5-7,7-9
# 2-8,3-7
# 6-6,4-6
# 2-6,4-8

# For the first few pairs, this list means:

#     Within the first pair of Elves, the first Elf was assigned sections 2-4
# (sections 2, 3, and 4), while the second Elf was assigned sections 6-8
# (sections 6, 7, 8).
#     The Elves in the second pair were each assigned two sections.
#     The Elves in the third pair were each assigned three sections: one got
# sections 5, 6, and 7, while the other also got 7, plus 8 and 9.

# This example list uses single-digit section IDs to make it easier to draw;
# your actual list might contain larger numbers. Visually, these pairs of
# section assignments look like this:

# .234.....  2-4
# .....678.  6-8

# .23......  2-3
# ...45....  4-5

# ....567..  5-7
# ......789  7-9

# .2345678.  2-8
# ..34567..  3-7

# .....6...  6-6
# ...456...  4-6

# .23456...  2-6
# ...45678.  4-8

# Some of the pairs have noticed that one of their assignments fully contains
# the other. For example, 2-8 fully contains 3-7, and 6-6 is fully contained by
# 4-6. In pairs where one assignment fully contains the other, one Elf in the
# pair would be exclusively cleaning sections their partner will already be
# cleaning, so these seem like the most in need of reconsideration. In this
# example, there are 2 such pairs.

# In how many assignment pairs does one range fully contain the other?

with open("P4.txt") as f:
    section_pairs = [line for line in f.read().strip().split()]

assignment_pairs = 0
for elfs in section_pairs:
    e1, e2 = [[int(x) for x in pairs.split("-")] for pairs in elfs.split(",")]
    e1, e2 = {x for x in range(e1[0], e1[1] + 1)}, {
        x for x in range(e2[0], e2[1] + 1)
    }
    if len(e1) == len(e1 | e2) or len(e2) == len(e1 | e2):
        assignment_pairs += 1

print(assignment_pairs)


# --- Part Two ---

# It seems like there is still quite a bit of duplicate work planned. Instead,
# the Elves would like to know the number of pairs that overlap at all.

# In the above example, the first two pairs (2-4,6-8 and 2-3,4-5) don't
# overlap, while the remaining four pairs (5-7,7-9, 2-8,3-7, 6-6,4-6, and
# 2-6,4-8) do overlap:

#     5-7,7-9 overlaps in a single section, 7.
#     2-8,3-7 overlaps all of the sections 3 through 7.
#     6-6,4-6 overlaps in a single section, 6.
#     2-6,4-8 overlaps in sections 4, 5, and 6.

# So, in this example, the number of overlapping assignment pairs is 4.

# In how many assignment pairs do the ranges overlap?

assignment_pairs_overlaps = len(section_pairs)
for elfs in section_pairs:
    e1, e2 = [[int(x) for x in pairs.split("-")] for pairs in elfs.split(",")]
    e1, e2 = {x for x in range(e1[0], e1[1] + 1)}, {
        x for x in range(e2[0], e2[1] + 1)
    }
    if len(e1 & e2) == 0:
        assignment_pairs_overlaps -= 1

print(assignment_pairs_overlaps)