Day 2 - C

README.md

@@ -4,7 +4,8 @@
 
 - [x] BASH
   - [Day 0](./day-0)
-- [] C
+- [x] C
+  - [Day 1](./day-1)
 - [] Clojure
 - [] Common LISP
 - [] C++

day-01/sol.c

@@ -0,0 +1,74 @@
+#include <stdio.h>
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+/*
+  USAGE: ./sol <inputfile>
+*/
+
+int get_my_score(char elf, char me)
+{
+  int elf_choice = (int)(elf - 'A') + 1;
+  int my_choice = (int)(me - 'X') + 1;
+  int i_won = 0;
+  if (elf_choice == my_choice)
+    return my_choice + 3;
+
+  switch (elf_choice + my_choice)
+  {
+  case 3:
+    i_won = (elf_choice == 1);
+    break;
+  case 4:
+    i_won = (elf_choice == 3);
+    break;
+  case 5:
+    i_won = (elf_choice == 2);
+    break;
+  }
+
+  return my_choice + i_won * 6;
+}
+
+const int wins[3] = {2, 3, 1};
+const int loss[3] = {3, 1, 2};
+
+int get_my_score_2(char elf, char me)
+{
+  int elf_choice = (int)(elf - 'A') + 1;
+  int outcome = (int)(me - 'X') + 1;
+
+  if (outcome == 2)
+    return elf_choice + 3;
+
+  if (outcome == 1)
+    return loss[elf_choice - 1];
+  return 6 + wins[elf_choice - 1];
+}
+
+int main(int argc, char *argv[])
+{
+  char *fileName = argv[1];
+
+  FILE *file = fopen(fileName, "r");
+  char line[256];
+  char elf, me;
+
+  int score1 = 0;
+  int score2 = 0;
+  while (1)
+  {
+    int i = fscanf(file, "%c %c\n", &elf, &me);
+    if (i == EOF)
+      break;
+    score1 += get_my_score(elf, me);
+    score2 += get_my_score_2(elf, me);
+  }
+
+  printf("Score one: %d\n", score1);
+  printf("Score two: %d\n", score2);
+
+  fclose(file);
+  return 0;
+}