2018/Day16/Day16A.c

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

typedef struct {
    uint8_t before[4];
    uint8_t opcode;
    uint8_t a, b, c;
    uint8_t after[4];
} Sample;

int sample_read(Sample *sample, FILE *file) {
    int read = 0;
    read +=
        fscanf(file,
               "Before: [%" SCNu8 ", %" SCNu8 ", %" SCNu8 ", %" SCNu8 "]\n",
               &sample->before[0], &sample->before[1], &sample->before[2],
               &sample->before[3]);

    read += fscanf(file, "%" SCNu8 " %" SCNu8 " %" SCNu8 " %" SCNu8 "\n",
                   &sample->opcode, &sample->a, &sample->b, &sample->c);

    read +=
        fscanf(file,
               "After: [%" SCNu8 ", %" SCNu8 ", %" SCNu8 ", %" SCNu8 "]\n\n",
               &sample->after[0], &sample->after[1], &sample->after[2],
               &sample->after[3]);

    return read == 12;
}

void sample_print(const Sample sample) {
    printf(
        "{\n"
        "  before: [%d, %d, %d, %d],\n"
        "  opcode: %d, a: %d, b: %d, c: %d,\n"
        "  after: [%d, %d, %d, %d]\n"
        "}\n",
        sample.before[0], sample.before[1], sample.before[2], sample.before[3],
        sample.opcode, sample.a, sample.b, sample.c,
        sample.after[0], sample.after[1], sample.after[2], sample.after[3]
    );
}

int sample_possible_opcodes(const Sample s) {
    int possible_opcodes = 0;

    // Addition
    if (s.after[s.c] == s.before[s.a] + s.before[s.b]) {
        printf("addr, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == s.before[s.a] + s.b) {
        printf("addi, ");
        possible_opcodes += 1;
    }

    // Multiplication
    if (s.after[s.c] == s.before[s.a] * s.before[s.b]) {
        printf("mulr, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == s.before[s.a] * s.b) {
        printf("muli, ");
        possible_opcodes += 1;
    }

    // Bitwise AND
    if (s.after[s.c] == (s.before[s.a] & s.before[s.b])) {
        printf("banr, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] & s.b)) {
        printf("bani, ");
        possible_opcodes += 1;
    }

    // Bitwise OR
    if (s.after[s.c] == (s.before[s.a] | s.before[s.b])) {
        printf("borr, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] | s.b)) {
        printf("bori, ");
        possible_opcodes += 1;
    }

    // Assignment
    if (s.after[s.c] == s.before[s.a]) {
        printf("setr, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == s.a) {
        printf("seti, ");
        possible_opcodes += 1;
    }

    // Greater-than testing
    if (s.after[s.c] == (s.a > s.before[s.b])) {
        printf("gtir, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] > s.b)) {
        printf("gtri, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] > s.before[s.b])) {
        printf("gtrr, ");
        possible_opcodes += 1;
    }

    // Equality testing
    if (s.after[s.c] == (s.a == s.before[s.b])) {
        printf("eqir, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] == s.b)) {
        printf("eqri, ");
        possible_opcodes += 1;
    }
    if (s.after[s.c] == (s.before[s.a] == s.before[s.b])) {
        printf("eqrr, ");
        possible_opcodes += 1;
    }

    return possible_opcodes;
}

int main(int argc, char **argv) {
    if (argc != 2) {
        printf("Usage: %s [input]\n", argv[0]);
        return EXIT_FAILURE;
    }

    FILE *file = fopen(argv[1], "r");
    Sample sample = {0};

    int gt3 = 0, samples = 0;
    while (sample_read(&sample, file)) {
        sample_print(sample);
        int possible_opcodes = sample_possible_opcodes(sample);
        printf("%d possible opcodes.\n\n", possible_opcodes);
        if (possible_opcodes >= 3) {
            gt3 += 1;
        }
        samples += 1;
    }
    printf("%d samples\n", samples);
    printf("%d\n", gt3);

    fclose(file);
    return EXIT_SUCCESS;
}