AoC18/day16p1/main.c

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

#include <glib.h>

#define REGS 4

enum instr_id {
    INSTR_ADDR,
    INSTR_ADDI,
    INSTR_MULR,
    INSTR_MULI,
    INSTR_BANR,
    INSTR_BANI,
    INSTR_BORR,
    INSTR_BORI,
    INSTR_SETR,
    INSTR_SETI,
    INSTR_GTIR,
    INSTR_GTRI,
    INSTR_GTRR,
    INSTR_EQIR,
    INSTR_EQRI,
    INSTR_EQRR,
    INSTR_ID_COUNT
};

struct instr {
    enum instr_id i;
    int a;
    int b;
    int c;
};

struct sample {
    int before[REGS];
    int after[REGS];
    struct instr instr;
};

const char *instr_str[] = {
    "addr",
    "addi",
    "mulr",
    "muli",
    "banr",
    "bani",
    "borr",
    "bori",
    "setr",
    "seti",
    "gtir",
    "gtri",
    "gtrr",
    "eqir",
    "eqri",
    "eqrr"
};

void instr_interpret(int *r, struct instr *i)
{
    switch (i->i) {
    case INSTR_ADDR:
    case INSTR_MULR:
    case INSTR_BANR:
    case INSTR_BORR:
    case INSTR_GTRR:
    case INSTR_EQRR:
        if (i->b >= REGS) return;
        // fallthrough
    case INSTR_ADDI:
    case INSTR_MULI:
    case INSTR_BANI:
    case INSTR_BORI:
    case INSTR_SETR:
    case INSTR_GTRI:
    case INSTR_EQRI:
        if (i->a >= REGS) return;
        // fallthrough
    case INSTR_SETI:
        if (i->c >= REGS) return;
        break;

    case INSTR_GTIR:
    case INSTR_EQIR:
        if (i->b >= REGS) return;
        if (i->c >= REGS) return;
        break;

    default:
        break;
    }

    switch (i->i) {
    case INSTR_ADDR: r[i->c] = r[i->a] + r[i->b]; break;
    case INSTR_ADDI: r[i->c] = r[i->a] + i->b; break;
    case INSTR_MULR: r[i->c] = r[i->a] * r[i->b]; break;
    case INSTR_MULI: r[i->c] = r[i->a] * i->b; break;
    case INSTR_BANR: r[i->c] = r[i->a] & r[i->b]; break;
    case INSTR_BANI: r[i->c] = r[i->a] & i->b; break;
    case INSTR_BORR: r[i->c] = r[i->a] | r[i->b]; break;
    case INSTR_BORI: r[i->c] = r[i->a] | i->b; break;
    case INSTR_SETR: r[i->c] = r[i->a]; break;
    case INSTR_SETI: r[i->c] = i->a; break;
    case INSTR_GTIR: r[i->c] = (i->a > r[i->b]) ? 1 : 0; break;
    case INSTR_GTRI: r[i->c] = (r[i->a] > i->b) ? 1 : 0; break;
    case INSTR_GTRR: r[i->c] = (r[i->a] > r[i->b]) ? 1 : 0; break;
    case INSTR_EQIR: r[i->c] = (i->a == r[i->b]) ? 1 : 0; break;
    case INSTR_EQRI: r[i->c] = (r[i->a] == i->b) ? 1 : 0; break;
    case INSTR_EQRR: r[i->c] = (r[i->a] == r[i->b]) ? 1 : 0; break;
    default: break;
    }
}

struct sample *parse_samples(const char *fname, int *len)
{
    FILE *f = fopen(fname, "r");
    if (!f) {
        perror(fname);
        return NULL;
    }

    GArray *array = g_array_new(FALSE, FALSE, sizeof(struct sample));

    // Haha what is proper parsing
    struct sample sample;
    while (fscanf(f,
            "Before: [%d, %d, %d, %d]\n"
            "%d %d %d %d\n"
            "After:  [%d, %d, %d, %d]\n\n",
            &sample.before[0], &sample.before[1],
            &sample.before[2], &sample.before[3],
            (int *)&sample.instr.i, &sample.instr.a,
            &sample.instr.b, &sample.instr.c,
            &sample.after[0], &sample.after[1],
            &sample.after[2], &sample.after[3]
            ) == 12) {
        g_array_append_val(array, sample);
    }

    fclose(f);

    *len = array->len;
    return (struct sample *)g_array_free(array, FALSE);
}

int main()
{
    int samples_len = 0;
    struct sample *samples = parse_samples("input", &samples_len);
    if (!samples) return 1;

    int *regs = g_new0(int, REGS);
    int result = 0;
    for (struct sample *sample = samples;
            sample < samples + samples_len; sample++) {
        int pass = 0;
        struct instr instr;
        memcpy(&instr, &sample->instr, sizeof(struct instr));
        for (enum instr_id i = 0; i < INSTR_ID_COUNT; i++) {
            instr.i = i;
            memcpy(regs, sample->before, sizeof(int) * REGS);
            instr_interpret(regs, &instr);
            if (memcmp(regs, sample->after, sizeof(int) * REGS) == 0) pass++;
        }

        if (pass >= 3) result++;
    }

    printf("%d/%d\n", result, samples_len);

    g_free(regs);
    g_free(samples);
    return 0;
}