banan-os/userspace/aoc2023/day2/main.cpp

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2023-12-02 16:10:37 +02:00
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#define MAX(a, b) ((a) < (b)) ? (b) : (a)
int parse_int_and_advance(const char*& ptr)
{
int result = 0;
while (isdigit(*ptr))
result = (result * 10) + (*ptr++ - '0');
return result;
}
int puzzle1(FILE* fp)
{
int result = 0;
char buffer[256];
while (fgets(buffer, sizeof(buffer), fp))
{
const char* ptr = buffer;
if (strncmp("Game ", ptr, 5))
continue;
ptr += 5;
int id = parse_int_and_advance(ptr);
ptr += 2;
bool valid = true;
while (*ptr && valid)
{
int count = parse_int_and_advance(ptr);
ptr++;
if (strncmp(ptr, "red", 3) == 0)
valid = (count <= 12);
if (strncmp(ptr, "green", 5) == 0)
valid = (count <= 13);
if (strncmp(ptr, "blue", 4) == 0)
valid = (count <= 14);
while (*ptr && !isdigit(*ptr))
ptr++;
}
if (valid)
result += id;
}
return result;
}
int puzzle2(FILE* fp)
{ int result = 0;
char buffer[256];
while (fgets(buffer, sizeof(buffer), fp))
{
const char* ptr = buffer;
if (strncmp("Game ", ptr, 5))
continue;
ptr += 5;
int id = parse_int_and_advance(ptr);
ptr += 2;
int needed_red = 0;
int needed_green = 0;
int needed_blue = 0;
while (*ptr)
{
int count = parse_int_and_advance(ptr);
ptr++;
if (strncmp(ptr, "red", 3) == 0)
needed_red = MAX(needed_red, count);
if (strncmp(ptr, "green", 5) == 0)
needed_green = MAX(needed_green, count);
if (strncmp(ptr, "blue", 4) == 0)
needed_blue = MAX(needed_blue, count);
while (*ptr && !isdigit(*ptr))
ptr++;
}
result += needed_red * needed_green * needed_blue;
}
return result;
}
int main(int argc, char** argv)
{
const char* file_path = "/usr/share/aoc2023/day2_input.txt";
if (argc >= 2)
file_path = argv[1];
FILE* fp = fopen(file_path, "r");
if (fp == nullptr)
{
perror("fopen");
return 1;
}
printf("puzzle1: %d\n", puzzle1(fp));
fseek(fp, 0, SEEK_SET);
printf("puzzle2: %d\n", puzzle2(fp));
fclose(fp);
}