Thread by @deivudesu

For this year's #AdventOfCode, my goal is to get each day's solution in the most readable format that will fit in a tweet. Striving for a compromise between conciseness and (subjective) elegance… 🧵

#AdventOfCode Day 1 (in Python 🐍):
# (relies on a few input assumptions)

data = [int(i) for i in open('01')]

print("Part 1:",
next(x*y for x in data for y in data if x+y == 2020))

print("Part 2:",
next(x*y*z for x in data for y in data for z in data if x+y+z == 2020))

#AdventOfCode Day 2 in 🐍

import re
L = [re.split('[: \-]', l) for l in open('02')]
L = [(int(p1), int(p2), [c == ch for c in pwd])
   for p1, p2, ch, _, pwd in L]

print("Part 1:",
sum(n1<= sum(m)<= n2 for n1, n2, m in L),
"Part 2:",
sum(m[p1-1]^m[p2-1] for p1, p2, m in L))

#AdventOfCode Day 3 in 🐍:

import math
G = [l.strip() for l in open('03')]
res = [sum(G[v][r*i % len(g[0])] == '#' for i,v in enumerate(range(0, len(G), d)))
　for r, d in ([1,1], [3,1], [5,1], [7,1], [1,2])]

print(f"Part 1:", res[1], "\nPart 2:", math.prod(res))

#AdventOfCode 4
import re
D = open('04').read().split('\n\n')

print('Pt 1:', sum(not(set(['byr','eyr','iyr','hgt','ecl','hcl','pid'])
- set(f[:3] for f in re.split('\s', d))) for d in D))

rng = {'b':(1920,2003), 'i':(2010,2021), 'e':(2020,2031),
'hcm':(150,194), 'hin':(59,77)}

print('Pt 2:',sum(sum([
*[int(d) in range(*rng.get(c[0]+u,[0])) for c,d,u in re.findall(r'([ebi]yr|hgt):(\d+)(in|cm)?\b',l)],
*[bool(re.search(p+r'\b',l)) for p in [
　'ecl:(amb|blu|brn|gry|grn|hzl|oth)',
　'hcl:#[\da-f]{6}',
　'pid:\d{9}']],
]) == 7
for l in D))

#AdventOfCode Day 5 in #Python. Nice and clean:

ids = [sum(2**i * (1 if b in 'BR' else 0) for i,b in enumerate(reversed(s.strip())))
for s in open('05')]

print("Part 1:", max(ids),
"\nPart 2:", next(s+1 for s in ids if s+1 not in ids and s+2 in ids))

#AdventOfCode2020 Day 6 in #Python

from collections import Counter
data = [
(Counter(l.replace('\n', '')), len(l.split('\n')))
for l in open('06').read().split('\n\n')
]

print('Pt 1:',
sum(len(g) for g,_ in data),

'\nPt 2:',
sum(v == t for g,t in data for v in g.values()))

#AdventOfCode Day 7 in #Python (2 tweets)

from collections import Counter
𝘽 = {
c1+c2: Counter({
k1+k2: int(n) for n, k1, k2 in zip(r[::4], r[1::4], r[2::4]) if n != 'no'
})
for c1, c2, _, _, *r in [l.split() for l in open('07')]
}
# 1/2

# 2/2 Day 7
ℱ = {}
def bags_in(b, n=1):
if b not in ℱ:
ℱ[b] = sum([bags_in(*x) for x in 𝘽[b].items()], 𝘽[b])
return Counter({c: ℱ[b][c]*n for c in ℱ[b]})

print('Pt1', sum('shinygold' in bags_in(b) for b in 𝘽),
'\nPt2', sum(bags_in('shinygold').values()))

#AoC Day 8

import networkx as nx
𝓟 = [(l[0], int(l[4:])) for l in open('08')]

G = nx.DiGraph((n,n+(a if c == 'j' else 1), {'a': (a if c == 'a' else 0)}) for n,(c,a) in enumerate(𝓟))
cy = nx.find_cycle(G, 0)

print('Pt 1:', nx.shortest_path_length(G, 0, cy[-1][0], 'a'))
# 1/2

nx.set_node_attributes(G, {n:{'i':a} for n,a in enumerate(𝓟)})
T= len(𝓟)
for s,t in cy:
　c,a= G.nodes[s]['i']
　u= s + {'j':1,'n':a,'a':0}[c]
　if nx.has_path(G,u,T):
　　G.remove_edge(s,t)
　　G.add_edge(s,u, a=0)
　　break
print('Pt 2:', nx.shortest_path_length(G,0,T,'a'))

#AoC 8 pure 🐍
𝓟 = [(l[:3],int(l[4:])) for l in open('08')]
def run(P):
　𝒜,IP,℮ = 0,0,set()
　while IP<len(P) and IP not in ℮:
　　℮.add(IP)
　　𝒾,a = P[IP]
　　if 𝒾=='jmp': IP+= a-1
　　if 𝒾=='acc': 𝒜+= a
　　IP+= 1
　return(IP >= len(P), 𝒜)
print('Pt 1', run(𝓟)[1])

for l,(𝒾,a) in enumerate(𝓟):
if 𝒾 == 'jmp':
𝒾 = 'nop'
elif 𝒾 == 'nop':
𝒾 = 'jmp'
b, acc = run(𝓟[:l] + [(𝒾,a)] + 𝓟[(l+1):])
if b:
print('Part 2:', acc)
break

#AoC D 9
N=[int(n) for n in open('09')]
p=25
ok=lambda n,S: any(1 for j in range(p) if n-S[j] in S[j+1:])

x=next(n for i,n in enumerate(N[p:]) if not ok(n,sorted(N[i:i+p])))

C=[]
for n in N:
　C+=[n]
　while sum(C)>x: C.pop(0)
　if len(C)>1 and sum(C)==x: print(x,min(C)+max(C))

#AdventOfCode 10
A= [int(i) for i in open('10')]
J= [0,*sorted(A),max(A)+3]
δ= [i-j for i,j in zip(J[1:],J)]
Δ=[1+p for p,d in enumerate(δ) if d==3]
𝓣=[1,1,2,4,7]
L=[𝓣[j-i-1] for i,j in zip([0]+Δ,Δ)]
import math
print('1:',len(Δ)*(len(δ)-len(Δ)),'2:',math.prod(L))

#AdventOfCode Day 11 in 🐍 (2 tweets)

D = [l.strip() for l in open('11')]
P = { (x,y): 1
for x, Y in enumerate(D)
for y, s in enumerate(Y) if s == 'L'}

Δ=[-1,0,1]

# 1/2

def s(P,𝝆,𝝉):
　N=lambda x,y:sum(next((P[x+r*h,y+r*v] for r in range(1,𝝆+1) if (x+r*h,y+r*v) in P),0) for h in Δ for v in Δ)
　while 1:
　　Q={p:N(*p)<𝝉+2 if P[p] else N(*p)==0 for p in P}
　　if P==Q: return sum(P.values())
　　P=Q
print('Pt1:',s(P,1,3),'Pt2:',s(P,len(D),4))

#AdventOfCode Day 12 in 🐍

# Move:
ℳ = lambda x,y,dx,dy,d: (x+d*dx, y+d*dy)

# Rotate:
cos, sin = [1,0,-1,0], [0,1,0,-1]
ℛ = lambda x,y,t: (x*cos[t]-y*sin[t], x*sin[t]+y*cos[t])

A = {'L': 90, 'R': -90}
𝓦 = { 1:[1,0], 2:[10,1] } # initial waypoints for part 1&2

# 1/2

for p,W in 𝓦.items():
　P= [0,0]
　for i in open('12'):
　　c,n= i[0],int(i[1:])
　　if c=='F': P=ℳ(*P,*W,n)
　　elif c in A: W=ℛ(*W, n//A[c]%4)
　　else:
　　　r= ℛ(1,0,'ENWS'.index(c))
　　　if p-1: W=ℳ(*W,*r,n)
　　　else: P=ℳ(*P,*r,n)
　print('Pt',p,abs(P[0])+abs(P[1]))

#AdventOfCode Day 13
t,B = open('13')
B = [(i,int(b)) for i,b in enumerate(B.split(',')) if b!='x']

x,y = min(((b-int(t)) % b, b) for _,b in B)
print('Pt 1:', x*y)

N,t = 1,0
for dt,b in B:
t = next(t for t in range(t,int(1e64),N) if (t+dt)%b==0)
N *= b
print('Pt 2:', t)

#AoC 14.1
import collections as c
L= [(0,b.strip()) if a[1]=='a' else (int(a[4:-2]),int(b)) for a,b in [l.split('=') for l in open('14')]]
ℜ= lambda m,x:int(m.replace('X',x),2)
M= c.defaultdict(int)
for a,b in L:
　if a:M[a]= (b|ℜ(m,'0')) & ℜ(m,'1')
　else: m=b
sum(M.values())

#Aoc 14.2
def A(m):
　if not m: yield ''; return
　for n in A(m[1:]):
　　for x in {'0':['X'], '1':['1'], 'X':['0','1']}[m[0]]: yield x+n
M= c.defaultdict(int)
for a,b in L:
　if a:
　　for n in A(m): M[(a | ℜ(n,'0')) & ℜ(n,'1')]= b
　else: m=b
print('Pt2:', sum(M.values()))

#AdventOfCode 15 🐍
D = [int(n) for n in open('15').read().split(',')]

for pt,stop in ([1,2020],[2,30000000]):
　S = {n:t for t,n in enumerate(D[:-1])}
　x = D[-1]
　for i in range(len(D), stop):
　　nx = i-1-S[x] if x in S else 0
　　S[x] = i-1
　　x = nx
　print(f'Pt {pt}:',x)

#AoC 16.1
import re
D= list(open('16'))
T= [int(i) for l in [D[22]]+D[25:] for i in l.split(',')]

R= [set([*range(int(a),int(b)+1), *range(int(c),int(d)+1)])
for _,a,b,c,d in [re.split(':|-|or ', r) for r in D[:20]]]

U= set.union(*R)
print('1:',sum(n for n in T if n not in U))

#16.2
M, *VT = [T[i:i+20] for i in range(0,len(T),20) if set(T[i:i+20]) <= U]

p = 1
for _ in range(20):
　for i in range(20):
　　F = [all(t[i] in r for t in VT) for r in R]
　　if sum(F) == 1:
　　　n = F.index(1)
　　　R[n] = {}
　　　if n < 6: p *= M[i]

print('Part 2:', p)

#AoC 17
G = lambda d: {(x,y, * [0]*(d-2))
　　 for y,X in enumerate(open('17').read().split('\n'))
　　 for x,c in enumerate(X) if c == '#'}

from itertools import product as pd

𝑅 = lambda X: range(min(X)-1, max(X)+2)
# 1/2

# 2/2

def GoL(d):
　𝑁 = lambda i: sum(tuple(a+b for a,b in zip(i,δ)) in P for δ in pd(*[[-1,0,1]]*d))
　P = G(d)

　for c in range(6):
　　P = {i for i in pd(*(𝑅([x[n] for x in P]) for n in range(d)))
　　　 if (i in P and 2<𝑁(i)<5) or 𝑁(i)==3}
　print(len(P))

GoL(3)
GoL(4)

#AoC Day 18
import ast as a
NT= a.NodeTransformer
cl= a.copy_location

class T1(NT):
　def visit_Sub(_,n): return cl(a.Mult(),n)
𝓔 = lambda s,T,D: eval(compile(T().visit(a.parse(s.translate(D),'','eval')),'','eval'))

print('Pt1:',sum(𝓔(l,T1,{42:'-'}) for l in open('18')))
#1/2

#2/2 #AdventOfCode Day 18 in 🐍

class T2(NT):
def visit_Add(_,n): return cl(a.Mult(),n)
def visit_Mult(_,n): return cl(a.Add(),n)

print('Pt2:', sum(𝓔(l, T2, {43:'*', 42:'+'}) for l in open('18')))
# 43 and 42 are ASCII for '+' and '*' respectively

#AoC 19
R,T= [t.split('\n') for t in open('19').read().split('\n\n')]
D= {k:v for k,v in [r.split(': ') for r in R]}
def B(r):
　if r in D: return B(D[r])
　if '"' in r: return r[1]
　j,s= ('|',' | ') if '|' in r else ('',' ')
　return f"({j.join(B(i) for i in r.split(s))})"
#1/2

#AdventOfCode Day 19 #2/2

import re
print('Part 1:', sum(bool(re.match(B('0')+'$', s)) for s in T))

P = "(" + '|'.join(f"{B('42')}{{{i+1},}}{B('31')}{{{i},{i}}}" for i in range(1,9)) + ")$"
# (I'm not proud…)

print('Part 2:', sum(1 for s in T if re.match(P,s)))

#AdventOfCode Day 20 will not fit in 2 tweets (not without some unspeakably ugly hacks)…

Instead, a reasonably elegant version that fits in less than 30 lines…

(GitHub version here: github.com/zedrdave/adven…)

#AdventOfCode Day 20

Oh, what the hell, here is a finely-crafted 4-tweet solution!
It's still surprisingly readable 😃

(check the screenshot for a commented version)

𝒏= '\n'
𝕛,𝕁= ''.join, 𝒏.join
from itertools import accumulate as 𝒞
P= {int(p[5:9]):p[11:] for p in open('20').read().split(2*𝒏)}

def 𝑻(p):
　X = {*𝒞(4*[p], lambda x,_: 𝕁(𝕛(l[::-1]) for l in zip(*x.split(𝒏))))}
　return X | {𝕁(l[::-1] for l in x.split(𝒏)) for x in X}

𝑬= lambda p,i: [p[:10],p[9::11],p[-10:],p[0::11]][i]
Z= {z for p in P for z in 𝑻(P[p])}
𝙈= lambda p,d: next((z for z in Z-𝑻(p) if 𝑬(z,(d+2)%4)==𝑬(p,d)), 0)

K = [k for k in P if sum(not 𝙈(P[k], i) for i in range(4)) == 2]
import math
print('Pt1',math.prod(K))

p= next(p for p in 𝑻(P[K[0]]) if (𝙈(p,2) and 𝙈(p,3)))
𝑳= lambda p,d: [*𝒞([p]+[d]*11, 𝙈)]

d=12
G = 𝕁( 𝕛(b[i:i+8] for b in B[::-1])
　for B in [𝑳(a,3) for a in 𝑳(p,2)]
　for i in range(d,90,d-1))

import regex as re
w= '[.#\n]{77}'
𝛹= f'#.{w+"#....#"*3}##{w}.#{"..#"*5}'

#AdventOfCode Day 20 in 🐍 4/4
for H in 𝑻(G):
m = len(re.findall(𝛹,H,0,0,-1,1)) # overlapped = True
if m: print('Part 2:', sum(c == '#' for l in G for c in l) - 15*m)

#AoC 21
F= [({*i.split()},{*a.split(', ')})
for i,a in [l.strip()[:-1].split(' (contains ') for l in open('21')]]
𝐔= set.union
A= 𝐔(*[a for _,a in F])
P= {aa: set.intersection(*[i for i,a in F if aa in a]) for aa in A}
print('Part 1:',sum(len(i-𝐔(*P.values())) for i,_ in F))

#AdventOfCode Day 21 in #Python #2/2
C = {}
while len(C) < len(P):
a,i = next((k,v) for k,v in P.items() if len(v) == 1)
C[a] = [*i][0]
P = {k:(v-i) for k,v in P.items()}

print('Part 2:', ','.join(v for k,v in sorted(C.items())))

#AdventOfCode Day 22 in 🐍
def 𝓟(p, q, P1=0):
　S={0}
　while p and q:
　　h = {(*p,0,*q)}
　　if h&S: return [1]
　　S |= h
　　c,d = p.pop(0),q.pop(0)
　　w = c>d if P1 or c>len(p) or d>len(q) else 𝓟(p[:c],q[:d])[0]
　　if w: p+=(c,d)
　　else: q+=(d,c)
　return (p,q)

# 1/2

#AdventOfCode Day 22 in #Python
# 2/2

for part in (1,2):
p,q = [[int(i) for i in p[10:].split('\n')]
for p in open('22/input.txt').read().split('\n\n')]

p,q = 𝓟(p,q, part==1)

print(f'Part {part}:', sum((i+1)*c for i,c in enumerate((p+q)[::-1])))

#AoC Day 23

def play(C, n):
　L= {k:v for k,v in zip(C, C[1:]+C[:1])}
　L[0]= 0
　c= C[0]
　for _ in range(n):
　　x= L[c]
　　y= L[x]
　　z= L[y]
　　L[c]= L[z]
　　d= c-1
　　while d in (x,y,z,0): d = d-1 if d else len(C)
　　L[z]= L[d]
　　L[d]= x
　　c= L[c]
　return L

#1/2

#adventofcode2020 Day 23 #2/2

C = [int(i) for i in open('23').read()]
L = play(C, 100)
c,s = L[1],''
while c != 1:
s += str(c)
c = L[c]
print('Part 1:', s)

n = 1000000
C += range(max(C)+1, n+1)
L = play(C, 10*n)
print('Part 2:', L[1]*L[L[1]])

#AoC 24
D= {'w':(-1,0),'nw':(0,-1),'ne':(1,-1),'e':(1,0),'se':(0,1),'sw':(-1,1)}
𝓜= lambda x,y,a,b: (x+a,y+b)

𝐓=set()
for l in open('24'):
　P=(0,0)
　while l.strip():
　　n= 2 if l[:2] in D else 1
　　P= 𝓜(*P,*D[l[:n]])
　　l= l[n:]
　𝐓 ^= {P}

print("Part 1:",len(𝐓))
#1/2

#AdventOfCode 24
#2/2
𝓝= lambda *p: sum(𝓜(*p,*D[k]) in 𝐓 for k in D)
𝓑= lambda n: range(min(x[n] for x in 𝐓)-1, max(x[n] for x in 𝐓)+2)
for d in range(100):
　𝐓= {(x,y) for x in 𝓑(0) for y in 𝓑(1) if ((x,y) in 𝐓 and 𝓝(x,y)==1) or 𝓝(x,y)==2}
print("Part 2:", len(𝐓))

#AoC 24: Animated!

for d in range(100):
　𝐓= {(x,y) for x in 𝓑(0) for y in 𝓑(1) if ((x,y) in 𝐓 and 𝓝(x,y)==1) or 𝓝(x,y)==2}
　w=38
　print('\033\143'+'\n'.join((' '*(y%2)+''.join('⬛️' if (x-w,y-w) in 𝐓 else '⬜️' for x in range(2*w))) for y in range(2*w)))
　time.sleep(.1)

#AdventOfCode 25

p1,p2 = [int(l) for l in open('25')]
def 𝓔(n, pk=0, l=-1):
　i,c = 0,1
　while True:
　　c = (c*n) % 20201227
　　if c == pk: return i
　　elif i == l: return c
　 i += 1
l1,l2 = 𝓔(7,p1),𝓔(7,p2)
assert 𝓔(p1,l=l2) == 𝓔(p1,l=l1)

print('🎄🎁⭐️', 𝓔(p1, l=l2))