aoc day 5 2021

awk1.awk

function hvcoo(p, f, hv) {
    if (hv == "h")
        return p SUBSEP f
    return f SUBSEP p
}

BEGIN { FS = ",| -> " }

$1 == $3 { hv = "v"; f = $1; a = $2; b = $4 }
$2 == $4 { hv = "h"; f = $2; a = $1; b = $3 }

a > b { t = a; a = b; b = t }

hv {
    while (a <= b)
        tot += (points[hvcoo(a++, f, hv)]++ == 1)
    hv = ""
}

END { print tot }

awk2.awk

BEGIN { FS = ",| -> " }

{ dx = dy = 0 }
$1 != $3 { dx = 2 * ($1 < $3) - 1 }
$2 != $4 { dy = 2 * ($2 < $4) - 1 }

{ x = $1; ex = $3 + dx }
{ y = $2; ey = $4 + dy }

{
    while (x != ex || y != ey) {
        tot += (points[x, y]++ == 1)
        x += dx; y += dy
    }
}

END { print tot }