advent 2021

advent.of.code.js

//1 - I
document.body.textContent.split("\n").map(Number).reduce(
    (acc, it) => it > acc[0] 
      ? [it, acc[1]+1] $
      : [it, acc[1]], 
    [9999, 0])[1]

//1 - II
(nums = document.body.textContent.split("\n").map(Number)).splice(3).reduce(
  (acc, it) => 
    [
        [...acc[0].slice(1), it], 
        [...acc[1],acc[0].reduce((a,i)=>a+i)]
    ], 
    [nums, []])[1].reduce(
  (acc, it) => it > acc[0]
    ? [it, acc[1]+1]
    : [it, acc[1]],
  [9999, 0])[1]


//2 - I
document.body.textContent.split("\n").reduce((acc, it) => {
  if(!it) return acc
	[action, steps] = it.split(" ")
  steps = parseInt(steps);
	switch(action){
    case 'forward': acc[0]+=steps; break;
    case 'up': acc[1]-=steps;break;  
    case 'down': acc[1]+=steps;break; 
  }
  return acc;
}, [0,0])


//2 - II
document.body.textContent.split("\n").reduce((acc, it) => {
  if(!it) return acc;
	[action, steps] = it.split(" ")
  steps = parseInt(steps);
  if(action == "forward" && acc[2] == 0){
    acc[0] += steps;
    return acc;
  }  
	switch(action){
    case 'forward': 
      acc[0] += steps;
      d = steps * acc[2]      
      acc[1] = acc[1] + (acc[2] > 0 ? d : -d);       
      break;
    case 'up': acc[2] -= steps;break;  
    case 'down': acc[2] += steps;break; 
  }
  return acc;
}, [0,0,0])


//3 - I
rows = document.body.textContent.split("\n"),
w = rows[0].length, h = rows.length, gamma = []
for(let i = 0; i < w; i++){
  let zeroes = 0
  for(let j = 0; j < h; j++) rows[j][i] == '0' && zeroes++
  gamma[i] = zeroes > h / 2 ? '0' : '1'
}
gamma = parseInt(gamma.join(""), 2)
epsilon = 2**w - 1 - gamma
epsilon*gamma

//3 - II
rows=document.body.textContent.split("\n")
    w = rows[0].length
  , h = rows.length;
calc = (arr, w, order = ['0', '1']) => {
  for(let i = 0; i < w; i++){
      zeroes = 0;
      for(let j = 0; j < arr.length; j++) if(arr[j][i] == '0') zeroes++
      for(let j = 0; j < arr.length; j++)
        if(zeroes >  arr.length / 2 && arr[j][i] == order[0]
        || zeroes <= arr.length / 2 && arr[j][i] == order[1]) delete arr[j]      
      arr=arr.filter(a=>a)
      if(arr.length == 1) break;  
  } 
  return arr
}
parseInt(calc([...rows], w),2)*parseInt(calc([...rows], w, ['1', '0']), 2)


// 4 - I
size=5,input=document.body.textContent.split(/\s+/g)
nums=input.shift().split(',')
boards=input.map(e=>[e,0]).reduce((acc, item, i) => { 
  !acc[(c=~~(i/(size**2)))] && (acc[c] = [item]) || acc[c].push(item)
  return acc
}, [])
done = 0;
nums.some(n=>{  
  boards.some((b,bi) => {
    if((f = b.map(i=>i[0]).indexOf(n)) > -1 && boards[bi][f]) boards[bi][f][1] = 1
    for(i=0;i<size;i++) if(b.filter((_,x) => x % size == i).filter(it=>it[1]).length == size
      || b.filter((_,x) => x % size == ~~(i/5) % 5).filter(it=>it[1]).length == size
      || b.slice(i*size, (i+1)*size).filter(it=>it[1]).length == size)
        done = [bi, n]
  })
  return done
})
boards[done[0]].map(a=>[+a[0],a[1]]).reduce((acc,i)=>i[1]?acc:acc+i[0], 0) * done[1]

// 4 - II
size=5,input=document.body.textContent.split(/\s+/g).filter(a=>a)
nums=input.shift().split(',')
boards=input.map(e=>[e,0]).reduce((acc, item, i) => { 
  !acc[(c=~~(i/(size**2)))] && (acc[c] = [item]) || acc[c].push(item)
  return acc
}, [])
done = 0
nums.some(n=>{  
  boards.some((b,bi) => {
    if((f = b.map(i=>i[0]).indexOf(n)) > -1 && boards[bi][f]) boards[bi][f][1] = 1
    for(i=0;i<size;i++) if(b.filter((_,x) => x % size == i).filter(it=>it[1]).length == size
      || b.filter((_,x) => x % size == ~~(i/5) % 5).filter(it=>it[1]).length == size
      || b.slice(i*size, (i+1)*size).filter(it=>it[1]).length == size)
         boards.filter(a=>a).length > 1 ? delete boards[bi] : (done = boards.filter(a=>a).length == 1 ? n : 0)
  })  
  return done
})
boards.filter(a=>a)[0].map(a=>[+a[0],a[1]]).reduce((acc,i)=>i[1]?acc:acc+i[0], 0)*done


//5 - I/II
document.body.textContent.split("\n").map(it=>it.split(/ -> |,/).map(Number)).reduce((acc, it) => {
  if(it[0] != it[2] && it[1] != it[3]) return acc //comment this line out for I
  ax=it[0],bx=it[2],ay=it[1],by=it[3],dx=bx-ax,dy=by-ay
  s=(a=Math.abs)(dx)>a(dy)?a(dx):a(dy),sx=dx/s,sy=dy/s
  for(i=0;i<s;i++) acc[idx=ax+(ay*1e6)]=acc[idx]+1||1
  ax+=sx,ay+=sy    acc[idx=ax+(ay*1e6)]=acc[idx]+1||1
  return acc
}, []).filter(i=>i>1).length


//6 - I/II
f=document.body.textContent.split(',').map(Number).reduce((a,i)=>(++a[i],a), new Array(9).fill(0)),d=256 //d=80 for I
while(d--)(n=f.shift(),f[8]=n,f[6]+=n)
f.reduce((a,i)=>a+i)


//7 - I
n=document.body.textContent.split(",").map(Number)
r=Infinity
for(t=0;t<n.length;t++) r=Math.min(r, n.reduce((a,i)=>a+Math.abs(i-t), 0))

//7 - II
n=document.body.textContent.split(",").map(Number)
r=Infinity,f=n=>n<=1?1:n+f(n-1)
for(t=0;t<n.length;t++) r=Math.min(r, n.reduce((a,i)=>a+f(Math.abs(i-t)), 0))