aoc/2022/3/solution.py

#!/usr/bin/python3
import sys

# part 1

def sort_ascii(string):
    return ''.join(sorted(string, key = lambda s: (sum(map(ord, s)), s)))

def map_ord(char):
    return ord(char) - 96 if ord(char) > 90 else ord(char) - 38

def part1():
    total = 0
    for line in sys.stdin:
        line = line.strip()
        left = sort_ascii(line[:len(line)//2])
        right = sort_ascii(line[len(line)//2:])
        #print(left, right)

        l = 0
        r = 0
        while l < len(left) and r < len(right):
            #print(l, left[l], r, right[r])
            if left[l] > right[r]:
                r += 1
            elif right[r] > left[l]:
                l += 1
            else:
                #print(left[l], right[r])
                total += map_ord(left[l])
                break
    pass
    print(total)

# part 2

def scan_three_lines():
    lines = []
    for i, line in enumerate(sys.stdin):
        if lines and i % 3 == 0:
            yield lines
            lines = []
        lines.append(line.strip())
    if (i + 1) % 3 == 0:
        yield lines

def reduce_identical(left, right):
    identical = set()
    l = 0
    r = 0
    while l < len(left) and r < len(right):
        if left[l] > right[r]:
            r += 1
        elif right[r] > left[l]:
            l += 1
        else:
            #print(left[l], right[r])
            identical.add(left[l])
            r += 1
            l += 1
    return identical

def part2():
    total = 0
    for l1, l2, l3 in scan_three_lines():
        #print(l1, l2, l3)
        a1 = reduce_identical(sort_ascii(l1), sort_ascii(l2))
        a2 = reduce_identical(sort_ascii(a1), sort_ascii(l3))
        #print(a2)
        total += map_ord(next(iter(a2)))
    print(total)

if sys.argv[1] in '1':
    part1()
else:
    part2()