day 1 part 1

day 1/day1.c

@@ -0,0 +1,79 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#define BUFFER_SIZE 1024
+
+int main(void) {
+  FILE *fp = fopen("input", "r");
+
+  size_t lineCount = 0;
+
+  char buffer[BUFFER_SIZE] = {0};
+
+  // get number of lines
+  size_t read = 0;
+
+  while ((read = fread(&buffer, sizeof(char), BUFFER_SIZE, fp))) {
+    for (size_t i = 0; i < read; i++) {
+      if (buffer[i] == '\n') {
+        lineCount++;
+      }
+    }
+  }
+
+  rewind(fp);
+
+  // get data from file
+  int* left = malloc(lineCount * 2 * sizeof(int));
+  // haha pointer arithmetic go brrr
+  int* right = left + lineCount * sizeof(int);
+
+  for (size_t i = 0; i < lineCount; i++) {
+    int leftNum, rightNum;
+    int numsGot = fscanf(fp, "%d   %d\n", &leftNum, &rightNum);
+
+    if (numsGot == 2) {
+      left[i] = leftNum;
+      right[i] = rightNum;
+    }
+  }
+
+  for (size_t i = 0; i < lineCount - 1; i++) {
+    int leftMin = i;
+    int rightMin = i;
+
+    for (size_t j = i + 1; j < lineCount; j++) {
+      if (left[j] < left[leftMin]) {
+        leftMin = j;
+      }
+
+      if (right[j] < right[rightMin]) {
+        rightMin = j;
+      }
+    }
+
+    if (leftMin != i) {
+      int temp = left[i];
+      left[i] = left[leftMin];
+      left[leftMin] = temp;
+    }
+
+    if (rightMin != i) {
+      int temp = right[i];
+      right[i] = right[rightMin];
+      right[rightMin] = temp;
+    }
+  }
+
+  int sum = 0;
+  for (size_t i = 0; i < lineCount; i++) {
+    sum += abs(left[i] - right[i]);
+  }
+
+  printf("%d\n", sum);
+
+  free(left);
+  fclose(fp);
+
+  return 0;
+}