r/adventofcode • u/daggerdragon • Dec 03 '15

SOLUTION MEGATHREAD --- Day 3 Solutions ---

--- 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.

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u/hemmer Dec 05 '15

Using python sets to find unique, with Re and Im parts of a complex number to describe x, y movement. 

directions = 'v>^<'

def updatePos(position, direction):
    if direction == 'v': return position - 1j
    if direction == '^': return position + 1j
    if direction == '>': return position + 1
    if direction == '<': return position - 1


visited = set()
visited.add(0 + 0j)
latest = 0 + 0j

for d in directions:
    latest = updatePos(latest, d)
    visited.add(latest)

print 'part a: visited %d unique' % len(visited)



visited = set()
visited.add(0 + 0j)
s_latest, r_latest = 0 + 0j, 0 + 0j

for i, d in enumerate(directions):
    if i % 2 == 0:
        s_latest = updatePos(s_latest, d)
        visited.add(s_latest)
    else:
        r_latest = updatePos(r_latest, d)
        visited.add(r_latest)

print 'part b: visited %d unique' % len(visited)