import gmp, random, strutils

const terms = 3

proc `$`(n: mpz_t): string =
  var cstr: cstring
  cstr = mpz_get_str(cstr, 10, n)
  return $cstr

proc getRandomMpzArr(): array[terms, mpz_t] =
  for i in 0..<terms:
    mpz_init result[i]
    mpz_set_si result[i], clong.rand

proc getExpSum(x: array[terms, mpz_t], debug = false, pow = 3): mpz_t =
  # Pretty-print the calculation to be performed (debug mode):
  if debug:
    var outStr: seq[string]
    for i in 0..<terms:
      outStr.add "$1**$2" % [$x[i], $pow]
    echo "(" & outStr.join(" + ") & ")"
  # Raise to exponent:
  var powX: array[terms, mpz_t]
  for i in 0..<terms:
    mpz_pow_ui powX[i], x[i], pow.culong
  if debug:
    echo "==\n(" & powX.join(" + ") & ")"
  # Calculate sum:
  var sum: mpz_t
  mpz_init sum
  for i in 0..<terms:
    mpz_add sum, sum, powX[i]
  if debug:
    echo "==\n$1\n" % $sum
  return sum

proc searchForTarget(loopsMax = int.high, targetMax = 2_000_000_000) =
  ## Tries random number combinations until their sum is <targetMax.
  randomize 19811019
  var mpzTargetMax: mpz_t
  mpz_init mpzTargetMax
  mpz_set_si mpzTargetMax, targetMax
  var loopCount = 0
  while loopCount < loopsMax:
    inc loopCount
    if loopCount %% 1_000_000 == 0:
      echo "Tried $1 combinations..." % $loopCount
    let x = getRandomMpzArr()
    let sum = getExpSum(x)
    let cmp = mpz_cmpabs(sum, mpzTargetMax)
    if cmp < 0:
      echo "SUCCESS!!!"
      discard getExpSum(x, true)
      quit 1

when isMainModule:
  searchForTarget()