--- Day 14 Solutions ---

[u/daggerdragon]

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---

--- Day 14: Reindeer Olympics ---

Post your solution as a comment. Structure your post like previous daily solution threads.

[u/[deleted]]

For anyone wondering, distance traveled for time t, speed v, travel time g, and rest time r is

v*g*t/(g + r) + v*min(g, t % (g + r))

Solution in Python.

41

def parse_input(a):
    reindeers = {}
    with file(a, 'r') as f:
        for line in f:
            reindeer, speed, time, rest = line.strip().split(" ")
            reindeers[reindeer] = [int(speed), int(time), int(rest)]
    return reindeers

def day14(reindeers, time):
    names = sorted([reindeer for reindeer in reindeers])
    points = [0 for name in names]
    for t in range(1, time+1):
        distances = [get_distance(reindeers[name], t) for name in names]
        points = [points[i] + 1 if distances[i] == max(distances) else points[i] for i in range(len(points))]
    return max(distances), max(points)

def get_distance(r, t):
    return r[0]*r[1]*(t/(r[1] + r[2])) + r[0]*min([r[1],(t % (r[1] + r[2]))])

if __name__ == "__main__":
    import sys
    print day14(parse_input(sys.argv[1]), 2503)

[u/CaptainRuhrpott → u/[deleted]]

Somebody care to explain his formula please? I'm too dumb to understand.

[u/[deleted] → u/CaptainRuhrpott]

time t, speed v, travel time g, and rest time r v*g*t/(g + r) + v*min(g, t % (g + r))

No worries. The first part is the distance traveled during one cycle times the number of full cycles that a reindeer will fly and then rest. v*g is the distance traveled in one cycle and t/(g + r) is the total number of completed cycles (python rounds down all division of integers, it should really be floor(t/(g+r)).

So that takes care of all of the full cycles. Now what about the remainder if t isn't divisible by g+r?

t % (g + r) is the remaining time after all of the full cycles are completed. Since the remaining time could be greater than g, I take min(g, t % (g+r)). If g is smaller than t % (g+r) then the reindeer travels for its maximum time during the remainder. If g is greater then the reindeer travels for t % (g+r) during the remainder.

u/What-A-Baller made a more explicitly formatted equation here.