abuse-chatot.cpp

#include <iostream>
#include <cstdint>
#include <vector>
#include <omp.h>

using namespace std;

typedef uint32_t u32;
typedef int64_t s64;

constexpr double C4 = 261.626;
constexpr double D4 = 293.665;
constexpr double E4 = 329.628;
constexpr double F4 = 349.228;
constexpr double G4 = 391.995;

struct LCG {
	uint32_t seed;

	LCG(uint32_t s) : seed(s) {}

	int rand();
};

u32 next_seed(u32 seed) {
    return seed * 0x41c64e6d + 0x6073;
}

u32 prev_seed(u32 seed) {
    return seed * 0xEEB9EB65 + 0x0A3561A1;
}

int LCG::rand() {
	seed = next_seed(seed);
	return seed >> 16;
}

bool valid_seed(u32 seed, double baseFreq, vector<double> expectedFreqs) {
    LCG lcg(seed);
    for (double expected : expectedFreqs) {
        double got = ((lcg.rand() % 8192) / 8192.0 * 0.25 + 1) * baseFreq;
        double ratio;
        if (expected < got) {
            ratio = got / expected;
        } else {
            ratio = expected / got;
        }
        if (ratio >= 1.015) {
            return false;
        }
    }
    return true;
}

bool good_seed(u32 seed) {
    int i;
    for (i = 0; i < 10; i ++) seed = prev_seed(seed);
    for (; i < 40; i ++) {
        u32 upper = seed >> 24;
        u32 hour = (seed >> 16) & 0xff;
        u32 frame = seed & 0xffff;
        u32 second = (frame - 17) / 60 + 10;
        if (12 * 24 + second - 256 <= upper && upper <= 12 * 24 + second + 60 - 256
            && hour < 24 && 0x0270 <= frame && frame <= 0x0400) {
            return true;
        }
        seed = prev_seed(seed);
    }
    return false;
}

int main() {
#ifdef _OPENMP
	fprintf(stderr, "OpenMP is enabled. max_threads=%d\n", omp_get_max_threads());
	fflush(stderr);
#endif
    //vector<double> expected = { E4, E4, F4, G4, G4, F4, E4, E4, E4 };
    //double base = 325;
    //bool select_good = false;
    
    vector<double> expected = {D4, C4, C4, D4, D4, D4};
    double base = 255;
    bool select_good = true;
    
#pragma omp parallel for
    for (s64 seed = 0; seed < 0x20000000; seed ++) {
        if (valid_seed(seed, base, expected) && (!select_good || good_seed(seed))) {
#pragma omp critical
            cout << seed << endl;
        }
    }
    cout << "finished" << endl;
    return 0;
}