Farey sequence: Difference between revisions

=={{header|Vlang}}==

{{trans|go}}

<lang go>struct Frac {

num int

den int

}

fn (f Frac) str() string {

return "$f.num/$f.den"

}

fn f(l Frac, r Frac, n int) {

m := Frac{l.num + r.num, l.den + r.den}

if m.den <= n {

f(l, m, n)

print("$m ")

f(m, r, n)

}

}

fn main() {

// task 1. solution by recursive generation of mediants

for n := 1; n <= 11; n++ {

l := Frac{0, 1}

r := Frac{1, 1}

print("F($n): $l ")

f(l, r, n)

println(r)

}

// task 2. direct solution by summing totient fntion

// 2.1 generate primes to 1000

mut composite := [1001]bool{}

for p in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31] {

for n := p * 2; n <= 1000; n += p {

composite[n] = true

}

}

// 2.2 generate totients to 1000

mut tot := [1001]int{init: 1}

for n := 2; n <= 1000; n++ {

if !composite[n] {

tot[n] = n - 1

for a := n * 2; a <= 1000; a += n {

mut f := n - 1

for r := a / n; r%n == 0; r /= n {

f *= n

}

tot[a] *= f

}

}

}

// 2.3 sum totients

for n, sum := 1, 1; n <= 1000; n++ {

sum += tot[n]

if n%100 == 0 {

println("|F($n)|: $sum")

}

}

}</lang>

{{out}}

<pre>Same as Go entry</pre>