adventofcode2021/aoc5-1.py

import pdb

class FloorMap:
    def __init__(self, size_x, size_y):
        self.board = []
        for _ in range(size_y+1):
            self.board.append([0]*(size_x+1))

    def add_line(self, start_pos, end_pos):
        if start_pos[0] == end_pos[0]:
            if start_pos[1] > end_pos[1]:
                start_pos, end_pos = end_pos, start_pos
            for i in range(start_pos[1], end_pos[1]+1):
                self.board[i][start_pos[0]] = self.board[i][start_pos[0]] + 1
        else:
            if start_pos[0] > end_pos[0]:
                start_pos, end_pos = end_pos, start_pos
            for i in range(start_pos[0], end_pos[0]+1):
                self.board[start_pos[1]][i] = self.board[start_pos[1]][i] + 1

    def count_inters(self):
        return sum([len([el for el in line if el >= 2]) for line in self.board])

    def __repr__(self):
        outstr = ""
        for line_num in range(10):
            outstr += f"{' '.join(str(self.board[line_num]))}"
        return outstr

    def __str__(self):
        outstr = ""
        for line_num in range(10):
            outstr += f"{' '.join(str(self.board[line_num]))}"
        return outstr


def main():
    with open("aoc5-1.txt", "r") as file:
        lines = [line.strip() for line in file.readlines()]
    # Each line is a pair of x,y coordinates...es separated by " -> " 
    lines = [[list(map(int, el.split(","))) for el in line.split(" -> ")] for line in lines]
    # For 5-1, only care about the ones where, of x1,y1 -> x2,y2, x1 == x2 or y1 == y2
    # i.e. only horizontal or vertical
    lines = [line for line in lines if line[0][0] == line[1][0] or line[0][1] == line[1][1]]
    # god, this feels goofy, but it works
    size_x = max([max(line[0][0], line[1][0]) for line in lines])
    size_y = max([max(line[0][1], line[1][1]) for line in lines])
    board_map = FloorMap(size_x, size_y)
    for line in lines:
        board_map.add_line(*line)
    print(board_map.count_inters())

if __name__ == "__main__":
    main()