StyleInCode

""" day_15_01.py """

# usage: python3 day_15_01.py < input

import sys
from collections import namedtuple


Point = namedtuple('GridPoint', 'x, y')


def find_bot(plan):
    """ where's Robbie """
    return [point for point, item in plan.items() if item == '@'][0]


def execute(commands, plan):
    """ command Robbie """
    deltas = {'^': (0, -1), '>': (1, 0), 'v': (0, 1), '<': (-1, 0)}
    cplan = plan.copy()
    i = find_bot(cplan)
    for move in commands:
        dx, dy = deltas[move]
        j = Point(i.x + dx, i.y + dy)
        match cplan[j]:
            case '.':
                cplan[i] = '.'
                cplan[j] = '@'
                i = j
            case 'O':
                while cplan[j] not in ['.', '#']:
                    j = Point(j.x + dx, j.y + dy)
                if cplan[j] == '.':
                    cplan[j] = 'O'
                    cplan[i] = '.'
                    j = Point(i.x + dx, i.y + dy)
                    cplan[j] = '@'
                    i = j

    return cplan


def ingest():
    """ parse standard input """
    plan = {}
    with sys.stdin as infile:
        point = Point(0, 0)
        for line in infile:
            if line.strip() == '':
                break
            for item in line.strip():
                plan[point] = item
                point = Point(point.x + 1, point.y)
            point = Point(0, point.y + 1)
        return infile.read().replace('\n', ''), plan


moves, grid = ingest()
grid = execute(moves, grid)
print(sum(x + 100 * y for (x, y), item in grid.items() if item == 'O'))