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advent of code 2021

day 07

the treachery of whales

pythonadvent of code 2021medianmean
python
def cost(l, n, f):
    return sum(f(e, n) for e in l)

for the first part, the solution is the median.

python
def median(l):
    return l[len(l) >> 1]

def part1(l):
    m = median(l)
    return cost(l, m, lambda x, y: abs(x - y))

for the second part, the solution is the average.

python
def part2(l):
    avg = sum(l) / len(l)
    f = lambda x, y: gauss(abs(x - y))
    return min(cost(l, ceil(avg), f), cost(l, floor(avg), f))