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Eratosthenes cribe in Scala and Python using tailrec
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import scala.annotation.tailrec | |
object criba { | |
def basic_get_primes(n: Int): List[Int] = { | |
val primes = List.range(2, n+1) | |
var max = Math.sqrt(n).toInt | |
@tailrec | |
def tal_rec(now: Int, prim: List[Int]): List[Int] = { | |
if(now >= max) prim | |
else if(prim contains now) | |
tal_rec(now+1,prim.filter((x: Int) => {x%now != 0 || x==now})) | |
else tal_rec(now+1, prim) | |
} | |
tal_rec(2, primes) | |
} | |
def get_primes(n: Int): List[Int] = { | |
val primes = List.range(2, n+1) | |
var max = Math.sqrt(n).toInt | |
@tailrec | |
def tal_rec(now: Int, prim: List[Int]): List[Int] = { | |
val n = prim(now) | |
if(n >= max) prim | |
else tal_rec(now+1,prim.filter((x: Int) => {x%n != 0 || x==n})) | |
} | |
tal_rec(0, primes) | |
} | |
//Tests! | |
basic_get_primes(100) | |
get_primes(100) | |
assert(basic_get_primes(10) == List(2,3,5,7,9)) | |
assert(get_primes(10) == List(2,3,5,7,9)) | |
} |
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import time | |
def tail_rec(fun): | |
def tail(fun): | |
a = fun | |
while callable(a): | |
a = a() | |
return a | |
return (lambda x: tail(fun(x))) | |
def basic_get_primes_tlr(n): | |
primes = list(range(2,n)) | |
max = int(n**(1/2)) | |
def tal_rec(now, prim): | |
if now >= max: | |
return prim | |
if now in prim: | |
prim = list(filter(lambda x: x%now != 0 or x==now, prim)) | |
return (lambda: tal_rec(now+1, prim)) | |
return tal_rec(2, primes) | |
def get_primes_tlr(n): | |
primes = list(range(2,n)) | |
max = int(n**(1/2)) | |
def tal_rec(now, prim): | |
n=prim[now] | |
if n >= max: | |
return prim | |
return (lambda: tal_rec(now+1, list(filter(lambda x: x%n != 0 or x==n, prim)))) | |
return tal_rec(0, primes) | |
def basic_get_primes(n): | |
primes = list(range(2,n)) | |
max = int(n**(1/2)) | |
def tal_rec(now, prim): | |
if now >= max: | |
return prim | |
if now in prim: | |
prim = list(filter(lambda x: x%now != 0 or x==now, prim)) | |
return tal_rec(now+1, prim) | |
return tal_rec(2, primes) | |
def get_primes(n): | |
primes = list(range(2,n)) | |
max = int(n**(1/2)) | |
def tal_rec(now, prim): | |
n = prim[now] | |
if n >= max: | |
return prim | |
return tal_rec(now+1, list(filter(lambda x: x%n != 0 or x==n, prim))) | |
return tal_rec(0, primes) | |
if __name__ == '__main__': | |
f = time.time() | |
basic_get_primes(900000) #TailRec Optimized | |
f2 = time.time() | |
print("basic_get_primes: %f" % (f2 - f)) | |
f = time.time() | |
get_primes(900000) #TailRec Optimized | |
f2 = time.time() | |
print("get_primes: %f" % (f2 - f)) | |
f = time.time() | |
tail_rec(basic_get_primes_tlr)(900000) #TailRec Optimized | |
f2 = time.time() | |
print("basic_get_primes_tlr: %f" % (f2 - f)) | |
f = time.time() | |
tail_rec(get_primes_tlr)(900000) #TailRec Optimized | |
f2 = time.time() | |
print("get_primes_tlr: %f" % (f2 - f)) | |
#print(basic_get_primes(100)) #TailRec normal | |
#print(tail_rec(get_primes_tlr)(2000000)) #TailRec Optimized |
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