C Day 3 (Part 1 only)

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

.vscode/launch.json

@@ -5,7 +5,7 @@
       "name": "(gdb) Start",
       "type": "cppdbg",
       "request": "launch",
-      "program": "${workspaceFolder}/c/day2.exe",
+      "program": "${workspaceFolder}/c/day3.exe",
       "args": [],
       "stopAtEntry": false,
       "cwd": "${workspaceFolder}/c/",

.vscode/tasks.json

@@ -0,0 +1,17 @@
+{
+	"version": "2.0.0",
+	"tasks": [
+		{
+			"type": "shell",
+			"label": "Run build script",
+			"command": "./build-all.ps1",
+			"options": {
+				"cwd": "${workspaceFolder}/c/"
+			},
+			"group": {
+				"kind": "build",
+				"isDefault": true
+			},
+		}
+	]
+}

c/build-all.ps1

@@ -1,2 +1,3 @@
-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
+# gcc day2/*.c -o day2.exe -Og -g -Wall -Werror -std=c17
+gcc day3/*.c -o day3.exe -Og -g -Wall -Werror -std=c17

c/day3/main.c

@@ -0,0 +1,119 @@
+// https://adventofcode.com/2021/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DAY 3
+#define INPUT_LENGTH 1000
+
+#define INPUT_BIT_SIZE 12
+
+unsigned int parsedInput[INPUT_LENGTH];
+
+void parseInput(char *const input)
+{
+  char const *curLine = input;
+  unsigned int lineNum = 0;
+  while (lineNum < INPUT_LENGTH)
+  {
+    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] = strtol(tempStr, NULL, 2);
+
+    free(tempStr);
+
+    curLine = nextLine ? nextLine + 1 : NULL;
+    lineNum++;
+  }
+}
+
+char const *const part1()
+{
+  unsigned int ones[INPUT_BIT_SIZE] = {0};
+
+  for (unsigned int input_i = 0; input_i < INPUT_LENGTH; input_i++)
+  {
+    for (unsigned char i = 0; i < INPUT_BIT_SIZE; i++)
+    {
+      ones[i] += (parsedInput[input_i] >> i) & 1;
+    }
+  }
+
+  char gammaStr[INPUT_BIT_SIZE + 1];
+  sprintf(gammaStr, "%c%c%c%c%c%c%c%c%c%c%c%c",
+          ones[INPUT_BIT_SIZE - 1] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 2] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 3] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 4] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 5] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 6] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 7] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 8] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 9] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 10] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 11] > INPUT_LENGTH / 2 ? '1' : '0',
+          ones[INPUT_BIT_SIZE - 12] > INPUT_LENGTH / 2 ? '1' : '0');
+
+  char epsilonStr[INPUT_BIT_SIZE + 1];
+  sprintf(epsilonStr, "%c%c%c%c%c%c%c%c%c%c%c%c",
+          ones[INPUT_BIT_SIZE - 1] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 2] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 3] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 4] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 5] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 6] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 7] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 8] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 9] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 10] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 11] > INPUT_LENGTH / 2 ? '0' : '1',
+          ones[INPUT_BIT_SIZE - 12] > INPUT_LENGTH / 2 ? '0' : '1');
+
+  long int gamma = strtol(gammaStr, NULL, 2);
+  long int epsilon = strtol(epsilonStr, NULL, 2);
+
+  char *const result = malloc(32);
+  sprintf(result, "%ld", gamma * epsilon);
+  return result;
+};
+
+char const *const part2()
+{
+  return "UNSOLVED";
+};
+
+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;
+}