aoc2021/c/day2.c

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

#define INPUT "../inputs/input-day2"

int
first()
{
    static char buf[256];
    static char cmd[256];
    static int  operand;

    int hpos = 0;
    int depth = 0;

    FILE *f = fopen(INPUT, "r");
    
    while(fgets(buf, 256, f)) {
        sscanf(buf, "%s %d\n", cmd, &operand);

        if(strcmp(cmd, "forward") == 0) {
            hpos += operand;
        } else if(strcmp(cmd, "up") == 0) {
            depth -= operand;
        } else if(strcmp(cmd, "down") == 0) {
            depth += operand;
        }
    }

    fclose(f);

    printf("depth: %d hpos: %d\n", depth, hpos);
    printf("result: %d\n", hpos * depth);

    return 0;
}

int
second()
{
    static char buf[256];
    static char cmd[256];
    static int  operand;

    int hpos = 0;
    int depth = 0;
    int aim = 0;

    FILE *f = fopen(INPUT, "r");
    
    while(fgets(buf, 256, f)) {
        sscanf(buf, "%s %d\n", cmd, &operand);

        if(strcmp(cmd, "forward") == 0) {
            hpos += operand;
            depth += (aim * operand);
        } else if(strcmp(cmd, "up") == 0) {
            aim -= operand;
        } else if(strcmp(cmd, "down") == 0) {
            aim += operand;
        }
    }

    fclose(f);

    printf("aim: %d depth: %d hpos: %d\n", aim, depth, hpos);
    printf("result: %d\n", hpos * depth);

    return 0;
}

int
main()
{
    first();
    second();
    return 0;
}