comments

day2/day2.c

@@ -13,18 +13,19 @@ long run(const long* input, size_t n, long noun, long verb);
 int main() {
   char input_str[350];
   memset(input_str, 0, 350*sizeof(char));
+  scanf("%s", input_str);
   long input[140];
   char* ptr = input_str;
   size_t i = 0;
-  scanf("%s", input_str);
-  while (*ptr != 0 && input_str - ptr < 350) {
+  while (*ptr != 0) { //read until null
     input[i] = strtol(ptr, &ptr, 10);
     i++;
-    ptr++;
+    ptr++; //skip the separator character (',')
   }
   size_t size = i;
   long out = run(input, size, 12, 2);
   printf("Value of mem[0] with noun=12, verb=2: %ld\n", out);
+  //try noun=0..99, verb=0..99
   for (i = 0; i < 100; i++) {
     for (long j = 0; j < 100; j++) {
       long out = run(input, size, i, j);
@@ -36,6 +37,17 @@ int main() {
   }
 }
 
+/**
+ * @brief run the Intcode state machine with given initial tape
+ *
+ * replace the values of mem[1] and mem[2] with noun and verb respectively before running
+ *
+ * @param input is a pointer to the tape
+ * @param n is the memory allocated
+ * @param noun replaces mem[1]
+ * @param verb replaces mem[2]
+ * @return
+ */
 long run(const long* input, size_t n, long noun, long verb) {
   long mem[n];
   memcpy((void*) mem, (const void*) input, n*sizeof(long));