⎕IO←1
]box on -style=max -trains=tree -fns=on
]rows on

DAY1←⊃⊃⎕NGET'data/2017/01.txt'1

DATA←DAY1,1⌷DAY1

+/⍎¨DATA[⍸2=/DATA] ⍝ Part 1: 1341

+/⍎¨DAY1[⍸=/⍉↑(DAY1)(DAY1⊖⍨2÷⍨≢DAY1)] ⍝ Part 2: 1348

DAY2←16 16⍴⍎¨'\d+'⎕S'&'⊢⊃⎕NGET'data/2017/02.txt'1

+/(⌈/-⌊/)DAY2 ⍝ Part 1: 39126

Day2←{target←1↑⍸{≠/0=⍺(|,|⍨)⍵}/¨cmb←,⍵∘.,⍵⋄÷/pair[⍒pair←target⊃cmb]}

+/Day2¨↓DAY2 ⍝ Part 2: 258

⎕IO←0
DAY3←325489

Square←{r←⍵*0.5⋄⍵=2*⍨⌊r:r⋄0≠2|⌈r:⌈r⋄1+⌈r} ⍝ Smallest odd number < the square root, unless perfect square

]dinput
Day3p1←{
    val←⍵
    width←Square ⍵                    ⍝ The width of the square in which the value is found
    edge←⌊((width*2)-val)÷(width-1)   ⍝ The side of the square: S E N W ← 0 1 2 3
    pos←edge⊃,size,-size∘.,-size,size←⌊width÷2  ⍝ Grid coords of corner
    _←(edge⊃,¯1 0∘.,0 ¯1)∘{pos+←⍺⋄⍵-1}⍣{⍺=val} (width*2)-edge×width-1  ⍝ Sequence at the nearest corner, acw
    +/|¨pos                           ⍝ Manhattan distance to centre
}

Day3p1 DAY3 ⍝ 552

]dinput
Coords←{
    ⍝ Generate all coordinate pairs for the circumference of a square ⍵
    pos←(⌊⍵÷2),(-⌊⍵÷2)+1
    
    E←(⊂pos)+0,¨⍳⍵-1
    N←(¯1↑E)+(-⍳⍵),¨0
    W←(¯1↑N)+0,¨-⍳⍵
    S←(¯1↑W)+(⍳⍵),¨0
    ∪E, N, W, S
}

Neighbours←{(⊂⍵)+(0 1)(1 1)(1 0)(1 ¯1)(0 ¯1)(¯1 ¯1)(¯1 0)(¯1 1)} ⍝ 8-neighbours

]dinput
Day3p2←{
    target←⍵
    seen←,⊂0 0 ⋄ vals←,1
    { ⍝ Move outwards one square at a time (i.e. odd numbers)
        found←{ ⍝ Walk circumference, adding up values from visible neighbours
            0=≢⍵:0
            pos←⊃1↑⍵
            old←seen⍳Neighbours pos
            newVal←+/vals[((≢seen)>old)/old]
            newVal>target:newVal
            vals,←newVal
            seen,←⊂pos
            ∇1↓⍵
        } Coords ⍵
        found>0:found
        ∇⍵+2
    } 3
}

Day3p2 325489 ⍝ 330785

⎕IO←1
DAY4←' '(≠⊆⊢)¨⊃⎕NGET'data/2017/04.txt'1

+/(∪≡⊢)¨DAY4 ⍝ Part 1: 325

+/(∪≡⊢)¨{⍵[⍋⍵]}¨¨DAY4 ⍝ Part 2: 119

⎕IO←1
DAY5←⍎¨⊃⎕NGET'data/2017/05.txt'1

]dinput
Day5←{
    instr←⍵
    modifier←⍺⍺
    1 {
        ip←1↑⍵
        jmp←ip⌷instr
        (ip+jmp)>≢instr:⍺
        instr[ip]+←modifier jmp
        (⍺+1)∇ip+jmp
    } 1
}

{1} Day5 DAY5 ⍝ Part 1: 372671

{⍵≥3:¯1⋄1} Day5 DAY5 ⍝ Part 2: 25608480 (takes a minute or so)

⎕IO←0
DAY6←2 8 8 5 4 2 3 1 5 5 1 2 15 13 5 14

]dinput
Redist←{
    (0@m⊢⍵) {                        ⍝ Zero out the current bin
        0=⊃⍵:⍺                       ⍝ Return end state
        (1∘+@n⊢⍺)∇(⊃⍵-1),n←16|1+⊢/⍵  ⍝ Move one index on, mod size and add 1. Decrease value to distribute.
    } ⍵[m],m←(⊢⍳⌈/)⍵                 ⍝ Value and index of the largest element
}

Day6p1←{seen←⊂⍵⋄e←Redist⍣{seen∊⍨⊂⍺:1⋄0⊣seen,←⊂⍺} ⍵⋄(⊂e),≢seen} ⍝ Stop if we've seen a state before.

(elem seen)←Day6p1 DAY6
seen ⍝ 3156

Day6p2←{count←0⋄target←⍵⋄_←Redist⍣{count+←1⋄⍺≡target} ⍵⋄count} ⍝ Stop when we revisit end state of part 1.

Day6p2 elem ⍝ Part 2: 1610

⎕IO←1
'segs'⎕CY'dfns'
DAY7←⊃⎕NGET'data/2017/07.txt'1

]dinput
Parse←{
    ⍺←⍬ ⍬ ⍬
    0=≢⍵:⍺
    items←'() ,->' segs ⊃1↑⍵
    (⍺,¨(⊂1⊃items)(⍎2⊃items)(⊂2↓items))∇1↓⍵
}

(nodes weights children)←Parse DAY7
⊃nodes~{⊃,/,⊆¨⍵}⍣≡children ⍝ Part 1: xegshds

]dinput
SubTreeWeight←{              ⍝ (nodes weights children) SubTreeWeight 'node'
    idx←(1⊃⍺)⍳⊂⍵             ⍝ Find the node's index
    0=≢idx⊃3⊃⍺:idx⊃2⊃⍺       ⍝ If node has no children -- return the weight
    (idx⊃2⊃⍺)++/⍺∘∇¨idx⊃3⊃⍺  ⍝ Add own weight to sum of child tree weights recursively
}

]dinput
FindAnomaly←{ ⍝ Find first key where its child trees all have the same weight
    idx←(1⊃⍺)⍳⊂⍵
    ch←idx⊃3⊃⍺
    0=≢ch:⍬
    chw←⍺∘SubTreeWeight¨ch
    (1≥≢∘∪)chw:⍵ (idx)      ⍝ Child tree weights all equal - we're done
    ⍺∇⊃ch[∊{∩/⍵}⌸chw]       ⍝ Intersect-reduce over unique indexes only returns non-empty for singles.
}

⊢ANOMALY←(nodes weights children) FindAnomaly 'xegshds'

PARENT←⍸{ANOMALY[1]∊⍵}¨children

TWEAK←|-/∪(nodes weights children)∘SubTreeWeight¨⊃children[PARENT]

weights[2⊃ANOMALY]-TWEAK ⍝ Part 2: 299

⎕IO←1
'segs'⎕CY'dfns'
DAY8←⊃⎕NGET'data/2017/08.txt'1

DATA←' ' segs¨DAY8

]dinput
Day8←{
    regs←∪{⊃,/,⊆¨⍵}⍣≡(↑⍵)[;1 5]
    R←regs∘⍳                       ⍝ By binding an operator, the static 'regs' vector is hashed
    vals←0⍴⍨≢regs
    Reg←{vals[R ⊂,⍵]}
    Set←{vals[R ⊂,⍺]←⍵⋄⍬}
    inc←{⍺ Set (Reg ⍺)+⍎⍵}
    dec←{⍺ Set (Reg ⍺)-⍎⍵}
    0 {
        0=≢⍵:(⌈/vals) ⍺
        max←⌈/vals,⍺
        instr←1⊃⍵
        rv←Reg 5⊃instr
        f←⍎2⊃instr
        ((,'>')≡6⊃instr)∧rv>⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        ((,'<')≡6⊃instr)∧rv<⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        ('=='≡6⊃instr)∧rv=⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        ('>='≡6⊃instr)∧rv≥⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        ('<='≡6⊃instr)∧rv≤⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        ('!='≡6⊃instr)∧rv≠⍎7⊃instr:max∇1↓⍵⊣(1⊃instr) f 3⊃instr
        max∇1↓⍵
    } ⍵
}

Day8 DATA ⍝ Part 1: 3745 Part2: 4644

⎕IO←1
DAY9←⊃⊃⎕NGET'data/2017/09.txt'1

]dinput
Day9←{
    pos←0
    str←⍵
    Yield←{pos+←1⋄pos⊃str}
    Skip←{⍺←0⋄c←Yield⍬⋄c='>':⍺⋄c='!':⍺∇⍬⊣Yield⍬⋄(⍺+1)∇⍬}
    (0 0 0) {
        3::1↓⍺  ⍝ Catch index error at end of input
        (depth total skipped)←⍺
        c←Yield⍬
        c='{':((1+depth),total,skipped)∇⍬
        c='}':((¯1+depth),(total+depth),skipped)∇⍬
        c='<':(depth,total,skipped+Skip⍬)∇⍬
        c='!':⍺∇⍬⊣Yield⍬
        ⍺∇⍬
    }⍬
}

Day9 DAY9 ⍝ Part 1: 10050 Part 2: 4482

⎕IO←0
'iotag'⎕CY'dfns'
DAY10←147 37 249 1 31 2 226 0 161 71 254 243 183 255 30 70

]dinput
Rot←{
    (skip pos len)←⍵
    0=len:(skip+1) (256|pos+len+skip) ⍺
    (skip+1) (256|pos+len+skip) (⊖@(256|pos iotag pos+len-1)⊢⍺)
}

Round←{0=≢⍵:⍺⋄((2⊃⍺) Rot (0⊃⍺) (1⊃⍺) (0⊃⍵))∇1↓⍵}

×/2↑2⊃(0 0,⊂⍳256)Round DAY10 ⍝ Part 1: 37230

]dinput
Knot←{
    lengths←(⎕UCS¨' '⎕R','⍕⍵),17 31 73 47 23
    sparse←(0 0,⊂⍳256) {
        0=⍵:2⊃⍺
        (⍺ Round lengths)∇⍵-1
    } 64
    ↓⍉{(⎕D,⎕A)[16⊥⍣¯1⊢⍵]} {2⊥⊃≠/(8⍴2)∘⊤¨⍵}¨↓16 16 ⍴ sparse
}

Knot DAY10 ⍝ 70b856a24d586194331398c7fcfa0aaf

⎕IO←1
DAY11←(∪⍳⊢)','(≠⊆⊢)⊃⊃⎕NGET'data/2017/11.txt'1 

HexMHD←{⌊2÷⍨+/|⍵} ⍝ Manhattan distance on a hex grid

DELTA←(¯1 0 1)(0 ¯1 1)(1 ¯1 0)(¯1 1 0)(1 0 ¯1)(0 1 ¯1) ⍝ SW S SE NW NE N -- order of index of first occurrance

HexMHD ⊃+/⊖DELTA[DAY11] ⍝ Part 1: 643

⌈/HexMHD¨+\DELTA[DAY11] ⍝ Part 2: 1471

⎕IO←0
'segs'⎕CY'dfns'
DAY12←1↓¨⍎¨¨' <->,'∘segs¨⊃⎕NGET'data/2017/12.txt'1 

]dinput
BFS←{              ⍝ nodes BFS node
    graph←⍺
    ⍬{
        0=≢⍵:⍺
        node←1↑⍵ ⋄ queue←1↓⍵
        ch←node⊃graph
        (⍺,node)∇(queue∪ch)~⍺
    }⍵
}

≢DAY12 BFS 0 ⍝ Part 1: 175

]dinput
ConnectedComponents←{
    graph←⍵
    seen←⍬
    0 {
        root←⍵
        root≥≢graph:⍺
        root∊seen:⍺∇⍵+1
        seen,←graph BFS root
        (⍺+1)∇⍵+1
    } 0
}

ConnectedComponents DAY12 ⍝ 213

⎕IO←0
'segs'⎕CY'dfns'
DAY13←⍎¨¨' :'∘segs¨⊃⎕NGET'data/2017/13.txt'1 

MAX←⊃⊃1↑¯1↑DAY13
IDX←⊣/↑DAY13
LEN←⊢/↑DAY13

Pos←{cycle←⍺-1⋄1=2|⌊⍵÷cycle:cycle-cycle|⍵⋄cycle|⍵} ⍝ depth Pos pico - the index at pico, for given depth

Day13p1←{fw←⍵⋄0{⍵≥≢fw:⍺⋄0=fw[⍵] Pos ⍵:(⍺+fw[⍵]×⍵)∇⍵+1⋄⍺∇⍵+1}0}

+/Day13p1 LEN@IDX⊢(1+MAX)⍴0 ⍝ Part 1: 2384

]dinput
Day13p2←{
    fw←⍵
    0 {                         ⍝ Current delay is ⍺
        ⍵≥≢fw:⍺
        0=fw[⍵]:⍺∇⍵+1           ⍝ Skip gaps
        0=fw[⍵] Pos ⍵+⍺:(⍺+1)∇0 ⍝ Caught! Increase delay and re-start from layer 0
        ⍺∇⍵+1                   ⍝ Still going: try the next layer
    } 0                         ⍝ Current layer
}

Day13p2 LEN@IDX⊢(1+MAX)⍴0  ⍝ Part 2: 3921270

⎕IO←0
'dec'⎕CY'dfns'   ⍝ Hex to dec helper function
DAY14←'jzgqcdpd'

ADJ←↑{∊{(8⍴2)⊤⍵}¨dec¨Knot DAY14,'-',⍕⍵}¨⍳128
+/∊ADJ  ⍝ Part 1: 8074

Bfs←{⍺←⍬⋄0=≢⍵:⍺⋄(⍺,1↑⍵)∇((1↓⍵)∪⍺⍺ 1↑⍵)~⍺}

Components←{⍺←0⋄0=≢⍵:⍺⋄(⍺+1)∇(1↓⍵)~⍺⍺ Bfs⊢1↑⍵}

]dinput
Connected←{
    valid←({(⍵[0]≥0)∧(⍵[1]≥0)∧(⍵[0]<128)∧(⍵[1]<128)}¨n)/n←⍵+(¯1 0)(1 0)(0 1)(0 ¯1)
    (1=⍺[valid])/valid
}

ADJ∘Connected Components ⊢ ⍸ADJ ⍝ Part 2: 1212

Part1←{⊢⍺⍺.prev←2147483647|⍺⍺.prev×⍺⍺.fact}
GA←({⍵⊣⍵.(prev fact)←679 16807}⎕NS'') Part1
GB←({⍵⊣⍵.(prev fact)←771 48271}⎕NS'') Part1

{⍺←0⋄0=⍵:⍺⋄(⍺+≡/{(16⍴2)⊤⍵}¨(GA⍬) (GB⍬))∇⍵-1} 40000000 ⍝ Part 1: 626 -- takes a good few mins to run

Part2←{0=⍺⍺.multiple|⍺⍺.prev←2147483647|⍺⍺.prev×⍺⍺.fact:⍺⍺.prev⋄∇⍬}
GA2←({⍵⊣⍵.(prev fact multiple)←679 16807 4}⎕NS'') Part2
GB2←({⍵⊣⍵.(prev fact multiple)←771 48271 8}⎕NS'') Part2

{⍺←0⋄0=⍵:⍺⋄(⍺+≡/{(16⍴2)⊤⍵}¨(GA2⍬) (GB2⍬))∇⍵-1} 5000000 ⍝ Part 2: 306 -- also takes a good few mins to run

⎕IO←0
'segs'⎕CY'dfns'

DAY16←',' segs⊢⊃⊃⎕NGET'data/2017/16.txt'1
Spin←{(-⍺)⊖⍵}
Exchange←{(a b)←⍺⋄⍵[b a]@a b⊢⍵}
Pair←{(⍵⍳⍺)Exchange ⍵}

]dinput
Day16←{
    ⍺←'abcdefghijklmnop'
    0=≢⍵:⍺
    cmd←⊃1↑⍵
    's'=cmd[0]:((⍎1↓cmd) Spin ⍺)∇1↓⍵
    'x'=cmd[0]:((⊃1↓'/'⎕VFI 1↓cmd) Exchange ⍺)∇1↓⍵
    ((∊'/'(≠⊆⊢)1↓cmd) Pair ⍺)∇1↓⍵
}

Day16 DAY16 ⍝ Part 1: kbednhopmfcjilag

'abcdefghijklmnop' {0=⍵:⍺⋄(⍺ Day16 DAY16)∇⍵-1} 100 ⍝ Part 2: fbmcgdnjakpioelh

⎕IO←0
DAY17←356

Insert←{(v cur st)←⍵⋄c←1+(≢⍺)|cur+st⋄c≥≢⍺:c (⍺,v)⋄c ((c↑⍺),v,c↓⍺)}

Day17p1←{2018=⍵:⍺⋄(cur buf)←⍺⋄(buf Insert ⍵ cur DAY17)∇⍵+1}

(cur buf)←0 (,0)Day17p1 1

buf⌷⍨cur+1 ⍝ Part 1: 808

Day17p2←{(cur target st)←⍵⋄cur←1+st|cur+DAY17⋄1=cur:cur,st,st+1⋄cur,target,st+1}

1⊃Day17p2⍣50000000⊢0 ¯1 1 ⍝ Part 2: 47465686 -- takes a minute or so to run

⎕IO←1
DAY18←{6::⍵⋄⍎⍵}¨¨' '(≠⊆⊢)¨⊃⎕NGET'data/2017/18.txt'1

]dinput
Day18←{
    mem←⍵
    ri←{'abfips'⍳⍵}         
    val←{(1=2|⎕DR)⍵:⍵⋄⍺[ri ⍵]}                     
    set←{(x y)←⍵⋄1∘+@7⊢(⍺ val y)@(ri x)⊢⍺}
    mul←{(x y)←⍵⋄1∘+@7⊢(⍺ val y)∘×@(ri x)⊢⍺}
    add←{(x y)←⍵⋄1∘+@7⊢(⍺ val y)∘+@(ri x)⊢⍺}
    mod←{(x y)←⍵⋄1∘+@7⊢(⍺ val y)∘|@(ri x)⊢⍺}
    rcv←{0≠⍺ val ⊃⍵:99∘+@7⊢⍺⋄1∘+@7⊢⍺}
    snd←{⍺ set 's' (⊃⍵)}
    jgz←{(x y)←⍵⋄(⍺ val x)>0:(⍺ val y)∘+@7⊢⍺⋄1∘+@7⊢⍺}
    {
        ip←¯1↑⍵
        instr←ip⊃mem⋄op←⊃instr
        ⍵ (⍎op) 1↓instr         
    }⍣{(¯1↑⍺)>≢mem}⍺
}

6⊃0 0 0 0 0 0 1 Day18 DAY18 ⍝ Part 1: 3423

MSG←{⍵⊣⍵.Queue←⍬ ⍬}⎕NS''

]dinput
Step←{
    pid←⍺
    mem←DAY18
    ri←{'abfip'⍳⍵}         
    val←{(1=2|⎕DR)⍵:⍵⋄⍺[ri ⍵]}                     
    set←{(x y)←⍵⋄1∘+@8⊢(⍺ val y)@(ri x)⊢⍺}
    mul←{(x y)←⍵⋄1∘+@8⊢(⍺ val y)∘×@(ri x)⊢⍺}
    add←{(x y)←⍵⋄1∘+@8⊢(⍺ val y)∘+@(ri x)⊢⍺}
    mod←{(x y)←⍵⋄1∘+@8⊢(⍺ val y)∘|@(ri x)⊢⍺}
    jgz←{(x y)←⍵⋄(⍺ val x)>0:(⍺ val y)∘+@8⊢⍺⋄1∘+@8⊢⍺}
    snd←{MSG.Queue[1+~pid],←⍺ val ⊃⍵⋄1∘+@7 8⊢⍺} ⍝ Add item to other's queue, and 1 to send-count and ip
    
    rcv←{                        ⍝ Pull item from message queue
        data←⊃MSG.Queue[1+pid]   
        0=≢data:1@6⊢⍺            ⍝ Blocked! Ip stays unchanged.
        val←1⊃data
        MSG.Queue[1+pid]←⊂1↓data ⍝ Pop queue
        0@6⊢⍺ set (⊃⍵) val       ⍝ Set reg with value from queue, and make note that we're not blocked
    }
    
    ip←¯1↑⍵
    ip>≢mem:⍵                    ⍝ Already terminated
    instr←ip⊃mem⋄op←⊃instr
    ⍵ (⍎⊃instr) 1↓instr
}

Deadlocked←{(p0 p1)←⍵⋄(p0[6]=1)∧p1[6]=1}
Terminated←{(p0 p1)←⍵⋄(p0[8]≥≢DAY18)∧p1[8]≥≢DAY18}
Done←{(Deadlocked ⍵)∨Terminated ⍵}

7⊃2⊃{⊃↓Step/0 1,⍪⍵}⍣{Done ⍺} (0 0 0 0 0 0 0 1)(0 0 0 0 1 0 0 1) ⍝ 'p' reg holds process id -- Part 2: 7493

⎕IO←1
DAY19←↑⊃⎕NGET'data/2017/19.txt'1
]rows on

]dinput
Turn←{
    graph←⍺
    (prev cur)←⍵
    Valid←{({(⍵[1]>0)∧(⍵[2]>0)∧(⍵[1]≤≢graph)∧⍵[2]≤≢graph}¨⍵)/⍵}
    ⊃(' '≠graph[coords])/coords←Valid (⊂prev)~⍨{cur+⍵}¨(¯1 0)(1 0)(0 ¯1)(0 1)
}

]dinput
Next←{ 
    (prev cur)←⍵
    dir←v÷(2*∘÷⍨+.×⍨)v←cur-prev          ⍝ Unit-vector in the direction of travel
    next←cur+dir
    ⍺[⊂cur]='+':cur (⍺ Turn prev cur) 1  ⍝ On a jct
    ⍺[⊂next]∊⎕A,⍺[⊂cur],'+':cur (next) 1 ⍝ Straight or coming to jct
    ⍺[⊂next]=' ':cur (cur) 0             ⍝ End of the track
    cur (next+dir) 2                     ⍝ Underpass
}

]dinput
Day19←{
    graph←⍺
    (⍬ 1) {
        (letters count)←⍺
        (prev cur delta)←graph Next ⍵
        graph[⊂cur]='Y':(letters,'Y') (count+delta)
        graph[⊂cur]∊⎕A:((letters,graph[⊂cur]) (count+delta))∇prev (cur)
        (letters (count+delta))∇prev (cur)
    } ⍵
}

⊢START←DAY19[1;]⍳'|'

DAY19 Day19 (0 START) (1 START) ⍝ Part 1: GPALMJSOY Part 2: 16204

⎕IO←0
DAY20←⊖1 0 2⍉(9÷⍨≢DATA)3 3⍴DATA←⍎¨'-?\d+'⎕S'&'⊢⊃⎕NGET'data/2017/20.txt'1 ⍝ 3 x 1000 x 3: acc vel pos

⊃⍋+/|2⌷+⍀⍣500⊢DAY20 ⍝ Part 1: 170

Day20p2←{state←+⍀⍵⋄hist←{⍵ (2>≢⍵)}⌸2⌷state⋄state[;∊(hist[;1])/hist[;0];]}

≢2⌷Day20p2⍣500⊢DAY20 ⍝ Part 2: 571

⎕IO←0
'segs'⎕CY'dfns'
DAY21←⍉↑'/'⎕R''¨↓⍉↑' =>'∘segs¨⊃⎕NGET'data/2017/21.txt'1

Rot←{(⍵)(⌽⍉⍵)(⌽⊖⍵)(⊖⍉⍵)}
Fold←{s←.5*⍨≢⍵⋄s s⍴⍵}
Trn←{m←Fold ⍵⋄∪(Rot m),(Rot⌽m),(Rot⊖m)}
Expand←{⍺←⍬⋄0=≢⍵:⍺⋄(k v)←⊃⍵⋄fv←Fold v⋄(⍺,{⍵ fv}¨Trn k)∇ 1↓⍵}
Tile←{2=⍺:,⊢∘⊂⌺(2 2⍴2 2)⊢⍵⋄1 1↓⊢∘⊂⌺(2 2⍴3 3)⊢0⍪0⍪0,0,⍵}
Day21←{s←2+2|≢⍵⋄tiles←,s Tile ⍵⋄dim←s÷⍨≢⍵⋄((⍴×⍴∘⊃)⍴0 2 1 3⍉↑)dim dim⍴{Find ⊂⍵}¨tiles}

TABLE←Expand ↓DAY21

Find←(⊣/↑TABLE)∘{⊃⊢/⊃TABLE[⍺⍳⍵]}

+/∊'#'=Day21⍣5⊢3 3⍴'.#...####' ⍝ Part 1: 162

+/∊'#'=Day21⍣18⊢3 3⍴'.#...####' ⍝ Part 2: 2264586

⎕IO←0

Make←{s←(2÷⍨⍺)-2÷⍨≢⍵⋄ctr←⊂s s⋄1@(ctr+⍸⍵)⊢⍺ ⍺⍴0} ⍝ Center data in larger array of shape ⍺ ⍺

DAY22←429 Make 25 25⍴(∪⍳⊢)∊⊃⎕NGET'data/2017/22.txt'1

]dinput
Day22p1←{
    m←⍺
    start←⌊2÷⍨≢m
    {
        (row col infected count dir)←⍵
        cur←m[row;col]
        m[row;col]←~cur
        newDir←cur {1=⍺:¯1∘⌽ ⍵⋄1∘⌽ ⍵} dir 
        newPos←(⊃newDir)⌷(⊂row col)(-,+)(1 0)(0 1)
        (⊃newPos),(infected+~cur) (count-1) (newDir)
    }⍣⍵⊢start start 0 ⍵ (⍳4)
}

2⊃DAY22 Day22p1 10000 ⍝ Part 1: 5261

]dinput
Day22p2←{
    m←0 2[⍺]     ⍝ Infected cells should have value 2
    start←⌊2÷⍨≢m
    {
        (row col infected count dir)←⍵
        cur←m[row;col]
        m[row;col]←cur⊃1 2 3 0
        newDir←cur {0=⍺:1⌽⍵⋄1=⍺:⍵⋄2=⍺:¯1⌽⍵⋄¯2⌽⍵} dir
        newPos←(⊃newDir)⌷(⊂row col)(-,+)(1 0)(0 1)
        (⊃newPos),(infected+2=m[row;col]) (count-1) (newDir)
    }⍣⍵⊢start start 0 ⍵ (⍳4)
}

2⊃DAY22 Day22p2 10000000 ⍝ Part 2: 2511927 -- takes around 90s to run

⎕IO←1
DAY23←{6::⍵⋄⍎⍵}¨¨' '(≠⊆⊢)¨⊃⎕NGET'data/2017/23.txt'1

]dinput
Day23←{
    mem←⍵
    ri←{'abcdefgh'⍳⍵}         
    val←{(1=2|⎕DR)⍵:⍵⋄⊃⍺[ri ⍵]}                     
    set←{(x y)←⍵⋄1∘+@10⊢(⍺ val y)@(ri x)⊢⍺}
    mul←{(x y)←⍵⋄1∘+@9⊢⍺ set x,(⍺ val x)×⍺ val y}
    sub←{(x y)←⍵⋄⍺ set x,(⍺ val x)-⍺ val y}
    jnz←{(x y)←⍵⋄(⍺ val x)≠0:(⍺ val y)∘+@10⊢⍺⋄1∘+@10⊢⍺}
    {
        ip←¯1↑⍵
        instr←ip⊃mem⋄op←⊃instr
        ⍵ (⍎op) 1↓instr         
    }⍣{(¯1↑⍺)>≢mem}⍺
}

9⊃0 0 0 0 0 0 0 0 0 1 Day23 DAY23 ⍝ Part 1: 5929

]dinput
r←Day23p2 ;b;c;h;d;f;e;g;v
(b c d e f g h)←107900 124900 0 0 0 0 0
:While 1
    (f d)←1 2

    :While 1
        e←2

        :If 0=d|b         ⍝ L4 hack
            v←⌊b÷d
            :If (v≥e)∧v<b
                f←0
            :EndIf
        :EndIf

        e←b
        d+←1
        g←d-b

        :If g=0
            :Leave
        :EndIf
    :EndWhile

    :If f=0
        h+←1
    :EndIf
    g←b-c

    :If g=0
        :Leave
    :EndIf

    b-←¯17
:EndWhile
r←h

Day23p2 ⍝ Part 2: 907

⎕IO←0
DAY24←⍎¨'/'⎕R','¨⊃⎕NGET'data/2017/24.txt'1

Find←{(a b)←↓⍉↑↑⍺⋄⍺[(⍸⍵=a)∪⍸⍵=b]}

]dinput
r←components Day24p1 args;path;pins;strongest;c;bridge
(path pins)←args
strongest←path
:For c :In (components~path) Find pins
    bridge←(components~c)Day24p1 (⊂(path,⊂c)),c {r←⍺~⍵⋄0=≢r:⊃⍺⋄⊃r} pins ⍝ Handle when both pins are equal
    :If (+/∊bridge)>+/∊strongest
        strongest←bridge
    :EndIf
:EndFor
r←strongest

+/∊DAY24 Day24p1 (⊂0 0) 0 ⍝ Part 1: 1511

]dinput
r←components Day24p2 args;path;pins;longest;c;bridge
(path pins)←args
longest←path
:For c :In (components~path) Find pins
    bridge←(components~c)Day24p2 (⊂(path,⊂c)),c {r←⍺~⍵⋄0=≢r:⊃⍺⋄⊃r} pins ⍝ Handle when both pins are equal
    :If (≢bridge)>≢longest
        longest←bridge
    :ElseIf ((≢bridge)=≢longest)∧(+/∊bridge)>+/∊longest
        longest←bridge
    :EndIf
:EndFor
r←longest

+/∊DAY24 Day24p2 (⊂0 0) 0 ⍝ Part 2: 1471

s←+/↑DAY24⋄n←1+⌈/∊DAY24⋄g←(⍳n)∘.∊DAY24⋄u←∘.≠⍨⍳≢DAY24
0{∨/c←⍵∧⍺⌷g:⌈/t+(-⍺-t←c/s)∇¨↓⍵∧⍤1⊢c⌿u⋄0}≡¨DAY24

STRENGTHS←+/↑DAY24      
COUNT←1+⌈/∊DAY24        
GRAPH←(⍳COUNT)∘.∊DAY24  
INVIDM←∘.≠⍨⍳≢DAY24      ⍝ Inverted identity matrix used to exclude the current item

]dinput
D24p1←{
    candidates←⍵∧⍺⌷GRAPH
    t←candidates/STRENGTHS
    ∨/candidates:⌈/t+(-⍺-t)∇¨↓⍵∧⍤1⊢candidates⌿INVIDM
    0
}

0 D24p1 ≡¨DAY24

⎕IO←0
STATE←6 6⍴1 1 1 0 ¯1 2 1 ¯1 0 1 1 3 1 1 0 0 ¯1 4 1 1 0 0 1 1 1 ¯1 5 1 ¯1 2 1 1 3 1 1 0

]dinput
Day25←{
    (pos state)←⍵
    args←(0 3[pos⊃TAPE])+⍳3
    (nv m ns)←STATE[state;args]
    TAPE[pos]←nv
    (pos+m) ns
}

TAPE←12919244⍴0⋄_←Day25⍣12919244⊢6459622 0⋄+/TAPE ⍝ 4287