C Day 2

Signed-off-by: Tobias Berger <tobi.berger13@gmail.com>

.vscode/launch.json

@@ -5,7 +5,7 @@
       "name": "(gdb) Start",
       "type": "cppdbg",
       "request": "launch",
-      "program": "${workspaceFolder}/c/day1.exe",
+      "program": "${workspaceFolder}/c/day2.exe",
       "args": [],
       "stopAtEntry": false,
       "cwd": "${workspaceFolder}/c/",

c/build-all.ps1

@@ -1 +1,2 @@
-gcc day1/*.c -o day1.exe -Og -g -Wall -Werror -std=c17
+gcc day1/*.c -o day1.exe -Og -g -Wall -Werror -std=c17
+gcc day2/*.c -o day2.exe -Og -g -Wall -Werror -std=c17

c/day2/main.c

@@ -0,0 +1,132 @@
+// https://adventofcode.com/2021/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DAY 2
+#define INPUT_LENGTH 1000
+
+struct Order
+{
+  enum Direction
+  {
+    FORWARD,
+    DOWN,
+    UP,
+  } direction;
+  int amount;
+} parsedInput[INPUT_LENGTH];
+
+void parseInput(char *const input)
+{
+  char *pch = strtok(input, " \n");
+  int orderNum = 0;
+  while (pch != NULL)
+  {
+    switch (pch[0])
+    {
+    case 'f':
+      parsedInput[orderNum].direction = FORWARD;
+      break;
+    case 'd':
+      parsedInput[orderNum].direction = DOWN;
+      break;
+    case 'u':
+      parsedInput[orderNum].direction = UP;
+      break;
+    default:
+      printf("Unknown direction: %s\n", pch);
+      exit(EXIT_FAILURE);
+    }
+
+    pch = strtok(NULL, " \n");
+    parsedInput[orderNum].amount = _atoi64(pch);
+
+    pch = strtok(NULL, " \n");
+    orderNum++;
+  }
+}
+
+char const *const part1()
+{
+  static unsigned int horizontal = 0;
+  static unsigned int depth = 0;
+
+  for (unsigned int i = 0; i < INPUT_LENGTH; i++)
+  {
+    switch (parsedInput[i].direction)
+    {
+    case FORWARD:
+      horizontal += parsedInput[i].amount;
+      break;
+    case DOWN:
+      depth += parsedInput[i].amount;
+      break;
+    case UP:
+      depth -= parsedInput[i].amount;
+      break;
+    }
+  }
+  char *const result = malloc(sizeof(char) * 50);
+  sprintf(result, "X: %d, Y: %d; Result: %d", horizontal, depth, horizontal * depth);
+  return result;
+};
+
+char const *const part2()
+{
+  static unsigned int horizontal = 0;
+  static unsigned int depth = 0;
+  static unsigned int aim = 0;
+
+  for (unsigned int i = 0; i < INPUT_LENGTH; i++)
+  {
+    switch (parsedInput[i].direction)
+    {
+    case FORWARD:
+      horizontal += parsedInput[i].amount;
+      depth += parsedInput[i].amount * aim;
+      break;
+    case DOWN:
+      aim += parsedInput[i].amount;
+      break;
+    case UP:
+      aim -= parsedInput[i].amount;
+      break;
+    }
+  }
+  char *const result = malloc(sizeof(char) * 50);
+  sprintf(result, "X: %d, Y: %d; Result: %d", horizontal, depth, horizontal * depth);
+  return result;
+};
+
+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;
+}