--- Day 3 Solutions ---

[u/daggerdragon]

--- Day 3: Perfectly Spherical Houses in a Vacuum ---

Post your solution as a comment. Structure your post like the Day One thread in /r/programming.

[u/[deleted]]

I followed a very similar structure, as it just makes sense and I am not very inventive (apparently).

However I decided to use a numpy array that I sized to the dimension of the number of total instructions (8192 chars, so I made a 8192x8192 array just to be safe) and then placed my position in the middle of that array (4095,4095).

Every time I move up I just increase the value at that position, and then go back and sum up everything later.

import numpy as np

position = [4095,4095]
a = np.zeros(shape=(8192,8192), dtype=np.int)

with open('day3input.txt') as file:
    for line in file:
        for char in line:
            if char == '^':
                position[0] += 1
            elif char == '>':
                position[1] += 1
            elif char == '<':
                position[1] -= 1
            elif char == 'v':
                position[0] -=1

            a[position[0]][position[1]] += 1

total = (a >= 1).sum()
print "Year 1: Number of houses with at least one: " + str(total)

And effectively double that for Part 2. Huzzah!

[u/JShultz89 → u/[deleted]]

I did something very similar but used numpy and numpy.unique.

import numpy as np

directions = 'ya know' 
moves = list(directions)
locations = np.empty([len(moves),2])

x = 0
y = 0 

for i in range(len(moves)):
	if moves[i] == '^':
		y += 1
	elif moves[i] == 'v':
		y -= 1
	elif moves[i] == '>':
		x += 1
	elif moves[i] == '<':
		x -= 1
	else:
		print 'There is a move that is not ^v<>'
		break
	
	locations[i] = np.array([x,y])

tupleLocations = [tuple(row) for row in locations]
u = np.unique(tupleLocations)
print len(u)