advent2021

Advent of Code 2021 Solutions
git clone git://bsandro.tech/advent2021
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commit 6f73f35dfebaab334028271e8d40c8e0485b7178
parent ec79421a5a9c955ee159e40b0dea1733b8bd1bf5
Author: bsandro <brian.drosan@gmail.com>
Date:   Thu,  2 Dec 2021 09:23:55 +0200

Day 02, puzzle 2

Diffstat:
Mday02/main.c | 6+++---
Aday02/puzzle2.c | 50++++++++++++++++++++++++++++++++++++++++++++++++++
Aday02/puzzle2.h | 1+
3 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/day02/main.c b/day02/main.c @@ -1,6 +1,6 @@ #include <stdio.h> #include "puzzle1.h" -//#include "puzzle2.h" +#include "puzzle2.h" int main(int argc, char *argv[]) { printf("Advent of Code: day 02\n"); @@ -17,8 +17,8 @@ int main(int argc, char *argv[]) { int counter1 = puzzle1(filename); printf("Puzzle #1: %d\n", counter1); - //int counter2 = puzzle2(filename); - //printf("Puzzle #2: %d\n", counter2); + int counter2 = puzzle2(filename); + printf("Puzzle #2: %d\n", counter2); return 0; } diff --git a/day02/puzzle2.c b/day02/puzzle2.c @@ -0,0 +1,50 @@ +#include <stdio.h> +#include <stdlib.h> +#include <errno.h> +#include <string.h> +#include <strings.h> + +#define MAX_LEN 32 +#define MAX_CMD 16 + +int puzzle2(const char *filename) { + FILE *infile = fopen(filename, "r"); + if (infile == NULL) { + fprintf(stderr, "fopen() error: %s\n", strerror(errno)); + return -1; + } + + static const char *cmd_up = "up"; + static const char *cmd_down = "down"; + static const char *cmd_forward = "forward"; + char buf[MAX_LEN] = {0}; + char cmd[MAX_CMD] = {0}; + int depth = 0; + int distance = 0; + int aim = 0; + int arg = 0; + + while (fgets(buf, MAX_LEN, infile) != NULL) { + if (sscanf(buf, "%15s %d", cmd, &arg) == 2) { + if (strncmp(cmd, cmd_up, MAX_CMD) == 0) { + aim -= arg; + } else if (strncmp(cmd, cmd_down, MAX_CMD) == 0) { + aim += arg; + } else if (strncmp(cmd, cmd_forward, MAX_CMD) == 0) { + distance += arg; + depth += aim * arg; + } else { + fprintf(stderr, "Invalid command string"); + break; + } + + bzero(buf, MAX_LEN); + bzero(cmd, MAX_CMD); + } + } + + // mutiny! ignoring feof/ferror. + + fclose(infile); + return depth * distance; +} diff --git a/day02/puzzle2.h b/day02/puzzle2.h @@ -0,0 +1 @@ +int puzzle2(const char *filename);