refactoring

day3.c

@@ -76,54 +76,48 @@ int manhattan(struct Point a, struct Point b) {
   return (abs(a.x - b.x) + abs(a.y - b.y));
 }
 
+//scan an input string, saving all the points to out. return the no. of points read
+size_t scan_points(char* in, struct Point* out){
+  //sequence is assumed to start at the origin.
+  out[0] = ORIGIN;
+  size_t i = 1;
+  while (*in != 0) { //read until null
+    char dir;
+    int delta;
+    int num_read;
+    sscanf(in, "%c%d%n", &dir, &delta, &num_read);
+    out[i] = get_pt(dir, delta, out[i]);
+    i++;
+    in += num_read + 1; // skip the number we just read, and the separator
+  }
+  return i;
+}
+
 int main() {
   //allocate an input string, and two arrays for input points
   //we don't know the exact length of the arrays but we know it's smaller than 400
   char* input_raw = calloc(1500,sizeof(char));
   scanf("%s", input_raw);
-  struct Point* a = calloc(400, sizeof(struct Point**));
-  struct Point* b = calloc(400, sizeof(struct Point**));
-  //Both a and b should start at the origin.
-  a[0] = ORIGIN;
-  b[0] = ORIGIN;
-  size_t a_index = 1;
-  size_t b_index = 1;
+  struct Point a[400];
+  struct Point b[400];
   char* ptr = input_raw;
-  while (*ptr != 0) { //read till null
-    char dir;
-    int delta;
-    int num_read;
-    sscanf(ptr, "%c%d%n", &dir, &delta, &num_read);
-    a[a_index] = get_pt(dir, delta, a[a_index-1]);
-    a_index++;
-    ptr += num_read + 1; // skip the number we just read, and the separator
-  }
+  size_t a_size = scan_points(ptr, a);
   //clear the input buffer
   memset((void*) input_raw, 0, sizeof(char)*1500);
   //scan the second input sequence, reset var ptr to the beginning of the string, reset location to the origin
   scanf("%s", input_raw);
   ptr = input_raw;
-  while (*ptr != 0) { //read until null
-    char dir;
-    int delta;
-    int num_read;
-    sscanf(ptr, "%c%d%n", &dir, &delta, &num_read);
-    b[b_index] = get_pt(dir, delta, b[b_index-1]);
-    b_index++;
-    ptr += num_read + 1; // skip the number we just read and the separator
-  }
-  free((void*) input_raw); // we don't need the raw input anymore
+  size_t b_size = scan_points(ptr, b);
+  free((void*) input_raw);
+  /*
+   * we want to find collisions between a and
+   */
   int min = INT_MAX;
   int min_delay = INT_MAX;
   int a_delay = 0;
-  for (size_t i = 0; i < a_index; i++) {
-  }
-  for (size_t i = 0; i < b_index; i++) {
-  }
-  //iterate over each combination of two edges in array of points a and b
-  for (size_t i = 1; i < a_index; i++) {
+  for (size_t i = 1; i < a_size; i++) {
     int b_delay = 0;
-    for (size_t j = 1; j < b_index; j++) {
+    for (size_t j = 1; j < b_size; j++) {
       struct Point pt = intersects(a[i-1], a[i], b[j-1], b[j]);
       int dist = manhattan(ORIGIN, pt);
       if (dist > 0) {