p19.c

//
//  main.c
//  p17
//
//  Created by Erik Aderstedt on 2019-12-16.
//  Copyright © 2019 Aderstedt Software AB-> All rights reserved.
//
#include <stdio.h>
#include "intcode.h"

int64_t *source;
size_t length;

#define MAX_NUM_OUTPUTS (10)

int64_t beam_at(int64_t x, int64_t y) {
    int64_t output[MAX_NUM_OUTPUTS];
    int64_t i[2];

    struct program *p = init_program_instance(source, length, output);
    i[0] = x;
    i[1] = y;
    p->input = i;
    p->remaining_inputs = 2;
    run_program_instance_until_halted(p);
    free_program_instance(p);

    return output[0];
}

int main(int argc, const char * argv[]) {
    source = load_source_code_from_file(argv[1], &length, 1000);

    size_t t = 0;
    for (int64_t x = 0; x < 50; x++) for (int64_t y = 0; y < 50; y++) if (beam_at(x,y)) t++;

    printf("Pt 1: %zu\n", t);

#define SQUARE_SIZE (100)
    int64_t x = 0, y = SQUARE_SIZE;

    while (1) {
        while (!beam_at(x, y)) x++;
        while (beam_at(x,y)) x++;
        x--;
        if (beam_at(x - (SQUARE_SIZE - 1), y + SQUARE_SIZE - 1)) {
            printf("Pt 2: %lld\n", (x - (SQUARE_SIZE - 1))*10000 + y);
            break;
        }
        y++;
    }

    free(source);
    exit(0);
}