adventofcode/2019/03a.py

# Python 3.7

def main(debug):
    paths = {}
    if debug:
        #paths = {1: ["R75","D30","R83","U83","L12","D49","R71","U7","L72"],
        #         2: ["U62","R66","U55","R34","D71","R55","D58","R83"]}
        paths = {1: ["R98","U47","R26","D63","R33","U87","L62","D20","R33","U53","R51"],
                 2: ["U98","R91","D20","R16","D67","R40","U7","R15","U6","R7"]}
    else:
        with open("03in.txt","r") as file:
            for i in range(2): # there are only two lines
                paths[i+1] = file.readline().strip("\n").split(",")
    grid = {}
    for i in range(2):
        pos = (0,0)
        for path in paths[i+1]:
            d, v = path[0], int(path[1:])
            if d == "U":
                dir = 1
                inc = 1
            elif d == "D":
                dir = 1
                inc = -1
            elif d == "R":
                dir = 0
                inc = 1
            else:
                dir = 0
                inc = -1
            for _ in range(v):
                a, b = pos
                if dir == 0:
                    a += inc
                else:
                    b += inc
                pos = (a,b)
                if pos not in grid:
                    grid[pos] = [0,0]
                grid[pos][i] = 1
    dists = []
    for k,v in grid.items():
        if v == [1,1] and k != (0,0):
            dists.append(abs(k[0]) + abs(k[1]))
    print(dists)
    print(min(dists))
            
if __name__ == "__main__":
    main(False)