adventofcode2020/day3b.py

from functools import reduce

def main():
    with open("input3.txt") as file:
        lines = file.readlines()
    grid = [list(line.strip()) for line in lines]
    print(grid[0])
    wrap = len(grid[0])
    treebumps = []
    routes = [[1,1],[3,1],[5,1],[7,1],[1,2]]
    for route in routes:
        coords = [0,0] # x, y - across, down
        trees = 0
        while coords[1] < len(grid):
            if grid[coords[1]][coords[0]] == "#":
                trees += 1
            coords[0] = coords[0] + route[0]
            coords[1] = coords[1] + route[1]
            if coords[0] >= wrap:
                coords[0] = coords[0] - wrap
        print(f"It's been a long toboggan trip going {route[0]} right and {route[1]} down, and I encountered {trees} trees.")
        treebumps.append(trees)
    total = reduce((lambda x,y: x*y), treebumps)
    print(f"I encountered these trees: {treebumps} - those produce {total}.")


if __name__ == "__main__":
    main()