AdventOfCode/c/day1/main.c

96 lines
2.2 KiB
C
Raw Normal View History

2021-12-01 10:06:58 +01:00
// https://adventofcode.com/2021/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define DAY 1
#define INPUT_LENGTH 2000
static int parsedInput[INPUT_LENGTH];
void parseInput(char const *const input)
{
char const *curLine = input;
unsigned int lineNum = 0;
while (curLine)
{
char const *nextLine = strchr(curLine, '\n');
int curLineLen = nextLine ? nextLine - curLine : strlen(curLine);
char *const tempStr = malloc(curLineLen + 1);
memcpy(tempStr, curLine, curLineLen);
tempStr[curLineLen] = '\0';
parsedInput[lineNum] = _atoi64(tempStr);
free(tempStr);
curLine = nextLine ? nextLine + 1 : NULL;
lineNum++;
}
}
char const *const part1()
{
static const unsigned char MEASUREMENTS = 2;
int result = 0;
for (unsigned int i = MEASUREMENTS - 1; i < INPUT_LENGTH; i++)
{
if (parsedInput[i] > parsedInput[i - 1])
{
result++;
}
}
char *const resultString = malloc(sizeof(char) * 10);
sprintf(resultString, "%d", result);
return resultString;
};
char const *const part2()
{
static const unsigned char MEASUREMENTS = 3;
int result = 0;
for (unsigned int i = MEASUREMENTS; i < INPUT_LENGTH; i++)
{
int measurementWindowA = parsedInput[i - 3] + parsedInput[i - 2] + parsedInput[i - 1];
int measurementWindowB = parsedInput[i - 2] + parsedInput[i - 1] + parsedInput[i - 0];
if (measurementWindowB > measurementWindowA)
{
result++;
}
}
char *const resultString = malloc(sizeof(char) * 10);
sprintf(resultString, "%d", result);
return resultString;
};
int main(void)
{
char *const fileName = malloc(sizeof(char) * sizeof("dayXX/input.txt"));
sprintf(fileName, "day%d/input.txt", DAY);
FILE *inputFile = fopen(fileName, "r");
if (inputFile == NULL)
{
printf("Failed to open input file %s.\n", fileName);
return 1;
}
fseek(inputFile, 0, SEEK_END);
long length = ftell(inputFile);
fseek(inputFile, 0, SEEK_SET);
char *const input = malloc(length);
if (input != NULL)
{
fread(input, 1, length, inputFile);
}
fclose(inputFile);
parseInput(input);
printf("Day %d\n", DAY);
printf("Part 1:\n%s\n", part1());
printf("--------------\n");
printf("Part 2:\n%s\n\n", part2());
return 0;
}