AC:NH turnip price calculator

TurnipPrices.cpp

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

// munged from https://github.com/simontime/Resead

namespace sead
{
class Random
{
public:
  void init();
  void init(uint32_t seed);
  void init(uint32_t seed1, uint32_t seed2, uint32_t seed3, uint32_t seed4);
  uint32_t getU32();
  uint64_t getU64();
  void getContext(uint32_t *seed1, uint32_t *seed2, uint32_t *seed3, uint32_t *seed4) const;

private:
  uint32_t mContext[4];
};

void Random::init()
{
  init(42069);
}

void Random::init(uint32_t seed)
{
  mContext[0] = 0x6C078965 * (seed ^ (seed >> 30)) + 1;
  mContext[1] = 0x6C078965 * (mContext[0] ^ (mContext[0] >> 30)) + 2;
  mContext[2] = 0x6C078965 * (mContext[1] ^ (mContext[1] >> 30)) + 3;
  mContext[3] = 0x6C078965 * (mContext[2] ^ (mContext[2] >> 30)) + 4;
}

void Random::init(uint32_t seed1, uint32_t seed2, uint32_t seed3, uint32_t seed4)
{
  if ((seed1 | seed2 | seed3 | seed4) == 0) // seeds must not be all zero.
  {
    seed1 = 1;
    seed2 = 0x6C078967;
    seed3 = 0x714ACB41;
    seed4 = 0x48077044;
  }

  mContext[0] = seed1;
  mContext[1] = seed2;
  mContext[2] = seed3;
  mContext[3] = seed4;
}

uint32_t Random::getU32()
{
  uint32_t n = mContext[0] ^ (mContext[0] << 11);

  mContext[0] = mContext[1];
  mContext[1] = mContext[2];
  mContext[2] = mContext[3];
  mContext[3] = n ^ (n >> 8) ^ mContext[3] ^ (mContext[3] >> 19);

  return mContext[3];
}

uint64_t Random::getU64()
{
  uint32_t n1 = mContext[0] ^ (mContext[0] << 11);
  uint32_t n2 = mContext[1];
  uint32_t n3 = n1 ^ (n1 >> 8) ^ mContext[3];

  mContext[0] = mContext[2];
  mContext[1] = mContext[3];
  mContext[2] = n3 ^ (mContext[3] >> 19);
  mContext[3] = n2 ^ (n2 << 11) ^ ((n2 ^ (n2 << 11)) >> 8) ^ mContext[2] ^ (n3 >> 19);

  return ((uint64_t)mContext[2] << 32) | mContext[3];
}

void Random::getContext(uint32_t *seed1, uint32_t *seed2, uint32_t *seed3, uint32_t *seed4) const
{
  *seed1 = mContext[0];
  *seed2 = mContext[1];
  *seed3 = mContext[2];
  *seed4 = mContext[3];
}
} // namespace sead

uint32_t pf(float f) {
  return *((uint32_t *)&f);
}
struct TurnipPrices
{
  int32_t basePrice;
  int32_t sellPrices[14];
  uint32_t whatPattern;
  int32_t tmp40;

  void calculate();

  // utility stuff for testing
  sead::Random rng;
  bool randbool()
  {
    return rng.getU32() & 0x80000000;
  }
  int randint(int min, int max)
  {
    return (((uint64_t)rng.getU32() * (uint64_t)(max - min + 1)) >> 32) + min;
  }
  float randfloat(float a, float b)
  {
    uint32_t val = 0x3F800000 | (rng.getU32() >> 9);
    float fval = *(float *)(&val);
    return a + ((fval - 1.0f) * (b - a));
  }
  int intceil(float val)
  {
    return (int)(val + 0.99999f);
  }
};

void TurnipPrices::calculate()
{
  basePrice = randint(90, 110);
  int chance = randint(0, 99);

  // select the next pattern
  int nextPattern;

  if (whatPattern >= 4)
  {
    nextPattern = 2;
  }
  else
  {
    switch (whatPattern)
    {
    case 0:
      if (chance < 20)
      {
        nextPattern = 0;
      }
      else if (chance < 50)
      {
        nextPattern = 1;
      }
      else if (chance < 65)
      {
        nextPattern = 2;
      }
      else
      {
        nextPattern = 3;
      }
      break;
    case 1:
      if (chance < 50)
      {
        nextPattern = 0;
      }
      else if (chance < 55)
      {
        nextPattern = 1;
      }
      else if (chance < 75)
      {
        nextPattern = 2;
      }
      else
      {
        nextPattern = 3;
      }
      break;
    case 2:
      if (chance < 25)
      {
        nextPattern = 0;
      }
      else if (chance < 70)
      {
        nextPattern = 1;
      }
      else if (chance < 75)
      {
        nextPattern = 2;
      }
      else
      {
        nextPattern = 3;
      }
      break;
    case 3:
      if (chance < 45)
      {
        nextPattern = 0;
      }
      else if (chance < 70)
      {
        nextPattern = 1;
      }
      else if (chance < 85)
      {
        nextPattern = 2;
      }
      else
      {
        nextPattern = 3;
      }
      break;
    }
  }

  whatPattern = nextPattern;

  /*
  if (checkGlobalFlag("FirstKabuBuy")) {
    if (!checkGlobalFlag("FirstKabuPattern")) {
      setGlobalFlag("FirstKabuPattern", true);
      whatPattern = 3;
    }
  }
  */

  for (int i = 2; i < 14; i++)
    sellPrices[i] = 0;
  sellPrices[0] = basePrice;
  sellPrices[1] = basePrice;

  int work;
  int decPhaseLen1, decPhaseLen2, peakStart;
  int hiPhaseLen1, hiPhaseLen2and3, hiPhaseLen3;
  float rate;

  switch (whatPattern)
  {
  case 0:
    // PATTERN 0: high, decreasing, high, decreasing, high
    work = 2;
    decPhaseLen1 = randbool() ? 3 : 2;
    decPhaseLen2 = 5 - decPhaseLen1;

    hiPhaseLen1 = randint(0, 6);
    hiPhaseLen2and3 = 7 - hiPhaseLen1;
    hiPhaseLen3 = randint(0, hiPhaseLen2and3 - 1);

    // high phase 1
    for (int i = 0; i < hiPhaseLen1; i++)
    {
      sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    }

    // decreasing phase 1
    rate = randfloat(0.8, 0.6);
    for (int i = 0; i < decPhaseLen1; i++)
    {
      sellPrices[work++] = intceil(rate * basePrice);
      rate -= 0.04;
      rate -= randfloat(0, 0.06);
    }

    // high phase 2
    for (int i = 0; i < (hiPhaseLen2and3 - hiPhaseLen3); i++)
    {
      sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    }

    // decreasing phase 2
    rate = randfloat(0.8, 0.6);
    for (int i = 0; i < decPhaseLen2; i++)
    {
      sellPrices[work++] = intceil(rate * basePrice);
      rate -= 0.04;
      rate -= randfloat(0, 0.06);
    }

    // high phase 3
    for (int i = 0; i < hiPhaseLen3; i++)
    {
      sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    }
    break;
  case 1:
    // PATTERN 1: decreasing middle, high spike, random low
    peakStart = randint(3, 9);
    rate = randfloat(0.9, 0.85);
    for (work = 2; work < peakStart; work++)
    {
      sellPrices[work] = intceil(rate * basePrice);
      rate -= 0.03;
      rate -= randfloat(0, 0.02);
    }
    sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    sellPrices[work++] = intceil(randfloat(1.4, 2.0) * basePrice);
    sellPrices[work++] = intceil(randfloat(2.0, 6.0) * basePrice);
    sellPrices[work++] = intceil(randfloat(1.4, 2.0) * basePrice);
    sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    for (; work < 14; work++)
    {
      sellPrices[work] = intceil(randfloat(0.4, 0.9) * basePrice);
    }
    break;
  case 2:
    // PATTERN 2: consistently decreasing
    rate = 0.9;
    rate -= randfloat(0, 0.05);
    for (work = 2; work < 14; work++)
    {
      sellPrices[work] = intceil(rate * basePrice);
      rate -= 0.03;
      rate -= randfloat(0, 0.02);
    }
    break;
  case 3:
    // PATTERN 3: decreasing, spike, decreasing
    peakStart = randint(2, 9);

    // decreasing phase before the peak
    rate = randfloat(0.9, 0.4);
    for (work = 2; work < peakStart; work++)
    {
      sellPrices[work] = intceil(rate * basePrice);
      rate -= 0.03;
      rate -= randfloat(0, 0.02);
    }

    sellPrices[work++] = intceil(randfloat(0.9, 1.4) * (float)basePrice);
    sellPrices[work++] = intceil(randfloat(0.9, 1.4) * basePrice);
    rate = randfloat(1.4, 2.0);
    sellPrices[work++] = intceil(randfloat(1.4, rate) * basePrice) - 1;
    sellPrices[work++] = intceil(rate * basePrice);
    sellPrices[work++] = intceil(randfloat(1.4, rate) * basePrice) - 1;

    // decreasing phase after the peak
    if (work < 14)
    {
      rate = randfloat(0.9, 0.4);
      for (; work < 14; work++)
      {
        sellPrices[work] = intceil(rate * basePrice);
        rate -= 0.03;
        rate -= randfloat(0, 0.02);
      }
    }
    break;
  }

  sellPrices[0] = 0;
  sellPrices[1] = 0;
}

int main(int argc, char **argv)
{
  TurnipPrices turnips;

  if (argc == 3)
  {
    turnips.whatPattern = atoi(argv[1]);
    turnips.rng.init(atoi(argv[2]));
  }
  else
  {
    printf("Usage: %s <pattern> <seed>\n", argv[0]);
    return 0;
  }

  turnips.calculate();
  printf("Pattern %d:\n", turnips.whatPattern);
  printf("Sun  Mon  Tue  Wed  Thu  Fri  Sat\n");
  printf("%3d  %3d  %3d  %3d  %3d  %3d  %3d\n",
         turnips.basePrice,
         turnips.sellPrices[2], turnips.sellPrices[4], turnips.sellPrices[6],
         turnips.sellPrices[8], turnips.sellPrices[10], turnips.sellPrices[12]);
  printf("     %3d  %3d  %3d  %3d  %3d  %3d\n",
         turnips.sellPrices[3], turnips.sellPrices[5], turnips.sellPrices[7],
         turnips.sellPrices[9], turnips.sellPrices[11], turnips.sellPrices[13]);

  return 0;
}

whatever pattern you give to the program, it still may get changed to a different pattern due to random number (according to the seed) (line 129), and if the final pattern is a 1, that is the high spike pattern. See line 233.

Example:

$  ./a.out 0 326
Pattern 1:
Sun  Mon  Tue  Wed  Thu  Fri  Sat
110   96  137  660  152   65   82
      91  200  180   91   63   80

$  ./a.out 0 291879
Pattern 1:
Sun  Mon  Tue  Wed  Thu  Fri  Sat
110   99  181  186   50   75   68
     106  660  120   86   60   55

For folks not familiar with the following C++ code:

  int randint(int min, int max)
  {
    return (((uint64_t)rng.getU32() * (uint64_t)(max - min + 1)) >> 32) + min;
  }
  float randfloat(float a, float b)
  {
    uint32_t val = 0x3F800000 | (rng.getU32() >> 9);
    float fval = *(float *)(&val);
    return a + ((fval - 1.0f) * (b - a));
  }

note that randint(a, b) returns something inclusive of a and b, and randfloat(a, b) returns something inclusive of a but exclusive of b.

You will see code which is randfloat(0.9, 0.85), and it is almost the same as randfloat(0.85, 0.9), except the first case is exclusive 0.85, while the second case is exclusive 0.9.

someone knows the mathematical formula necessary in this program? I want to do a mathematical investigation around Turnip Prophet, but I don't really understand about programming

I used this code to build a simulator sampling the market for 1,000,000 weeks:

https://brettonw.com/turnips/

I used this code to build a simulator sampling the market for 1,000,000 weeks:

https://brettonw.com/turnips/

Pretty cool! I am glad to report that my own simulation agrees with your Wednesday morning strategy.

I like how you made an analysis of the return as a function of how many friends you have. Nice work!

This is really cool info. I have a different use case: I time travel to various Wednesdays to look for prices greater than 300. When I find that price, I'll use a second switch and ACNH to go to Sunday, buy tons of turnips, and fly to the first switch and sell the turnips. Very nice profit. However the big thing is to find the Wednesday via time travel. It can take hours to find the right day and time. I've used the MeteoNook to find exact times when meteors show up, and was wondering if a similar algorithm could tell me the exact day and time, or at least narrow it down a bit. I'm guessing not, since there is that random function, but thought I'd check around.