Source code in the v programming language

const max_size = 10

fn factorial_i() {
  mut facs := [0].repeat(max_size + 1)
  facs[0] = 1
  println('The 0-th Factorial number is: 1')
  for i := 1; i <= max_size; i++ {
    facs[i] = i * facs[i - 1]
    num := facs[i]
    println('The $i-th Factorial number is: $num')
  }
}

fn main() {
	factorial_i()
}

const max_size = 10

fn factorial_r(n int) int {
  if n == 0 {
    return 1
  }
  return n * factorial_r(n - 1)
}

fn main() {
  for i := 0; i <= max_size; i++ {
    println('factorial($i) is: ${factorial_r(i)}')
  }
}

const max_size = 10

fn factorial_tail(n int) int {
	sum := 1
	return factorial_r(n, sum)
}

fn factorial_r(n int, sum int) int {
  if n == 0 {
    return sum
  }
  return factorial_r(n - 1, n * sum )
}

fn main() {
  for i := 0; i <= max_size; i++ {
    println('factorial($i) is: ${factorial_tail(i)}')
  }
}

const max_size = 10

struct Cache {
mut:
  values []int
}

fn fac_cached(n int, mut cache Cache) int {
  is_in_cache := cache.values.len > n
  if is_in_cache {
    return cache.values[n]
  }
  fac_n := if n == 0 { 1 } else { n * fac_cached(n - 1, mut cache) }
  cache.values << fac_n
  return fac_n
}

fn main() {
  mut cache := Cache{}
  for n := 0; n <= max_size; n++ {
    fac_n := fac_cached(n, mut cache)
    println('The $n-th Factorial is: $fac_n')
  }
}