Day 9: 325

day9.hs

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+import Data.List
+s=scanl
+v=[-1..1]
+r=replicate
+h%t=t+signum(h-t)
+p(d:_:i)=r(read i)d
+(h:l)&d=s(?)(zipWith(+)(z[d])h)l
+[x,y]!t=elem t[[x+n,y+m]|n<-v,m<-v]
+h@[x,y]?t@[a,b]|h!t=t|let=[x%a,y%b]
+w i=length.nub.map last.(s(&)$r i[0,0])
+z"U"=[1,0];z"D"=[-1,0];z"L"=[0,-1];z"R"=[0,1]
+main=interact$show.((,).w 10<*>w 2).(p=<<).lines

day9short

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+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2

day9short2

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+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20