面白い問題おしえて〜な 27問目

import Data.List

n = 30

samples = [ t | x1<-[1..n],x2<-[1..n],y1<-[1..n],y2<-[1..n],let s = nub $ sort [x1,x2,y1,y2],length s == 4, let [a1,a2] = sort [x1,x2],let [b1,b2] = sort [y1,y2],let t=[a1,a2,b1,b2]]

pl [a1,a2,b1,b2] = (if a1 < b1 then 1 else 0) + (if a2 < b2 then 1 else 0)
pls = map pl samples

main = do
print $ length $ filter (==0) pls
print $ length $ filter (==1) pls
print $ length $ filter (==2) pls