Condition is: You have to use (map or filter、concat、if sentence.)
Please help me!
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filter(lambda (x, y, z): x*x + y*y == z*z, [(a, b, c) for a in range (1, n+1) for b in range (a, n+1) for c in range(b, n+1)])

obviously, the haskell and python versions are idea-wise isomorphic.

and here’s a kind of O(n^2) version . the range for the multiplying factor (mu) is off the top of my head, and is there to take the output from the p-q stuff (eg (3,4,5)) and get the derived triplets (eg (6,8,10) and (12,16,20)). i say “kind of” O(n^2) because the generation of unique triplets is O(n^2) at minimum, and multiplying each of the integers in the triplet to get all the derived triplets is an additional operation. i don’t have the upper bound for the multiplying factor, though if it can be proved that such a bound exists and is independent of n, the algorithm would become strictly — as opposed to “kind of” — O(n^2)

filter(lambda (a, b, c): max(a, b, c) <= n, [(p*q*mu, ((p**2 - q**2)/2)*mu, ((p**2 + q**2)/2)*mu) for q in range(1,n,2) for p in range(q+2,n,2) for mu in range(1, 5)])

def f(n:Int) = for(x <- 1 to n; y <- (x+1) to n; z <- (y+1) to n; if x*x + y*y == z*z) yield (x,y,z);

The Scala compiler infers the return type of the function, Seq[(Int,Int,Int)], and compiles the code into statically-typed JVM bytecodes.