[REFACTOR] [Hacker Rank] Warmup: Time Conversion solved ✅. Triying to fix sonarlint detected issues.

Author: Gonzalo Diaz

src/lib/exercises/src/hackerrank/warmup/time_conversion.c

@@ -40,24 +40,23 @@ char *HACKERRANK_WARMUP_getStringFragment(const char *s, unsigned long len,
 }
 
 char *HACKERRANK_WARMUP_timeConversion(const char *s) {
+  if (s == NULL) {
+    return NULL;
+  }
+
+  const unsigned int TIME_SIZE = 11; // hh:mm:ssXX 10 + 1 for null terminator
+
   char *meridian = HACKERRANK_WARMUP_getLast(s, 2);
   char *hour_str = HACKERRANK_WARMUP_getFirst(s, 2);
 
-  char *time_str = (char *)malloc((strlen(s) + 1) * sizeof(char));
-  if (time_str == NULL) {
-    free(hour_str);
-    free(meridian);
-    return NULL;
-  }
+  char time_str[TIME_SIZE];
   strcpy(time_str, s);
-  char *temp_time_str;
+  const char *temp_time_str;
   unsigned long time_str_len = strlen(time_str);
   temp_time_str = HACKERRANK_WARMUP_getLast(time_str, time_str_len - 2);
-  free(time_str);
-  time_str = temp_time_str;
+  strcpy(time_str, temp_time_str);
   temp_time_str = HACKERRANK_WARMUP_getFirst(time_str, time_str_len - 2);
-  free(time_str);
-  time_str = temp_time_str;
+  strcpy(time_str, temp_time_str);
 
   char *endptr;
   long hour = strtol(hour_str, &endptr, 10);
@@ -67,7 +66,6 @@ char *HACKERRANK_WARMUP_timeConversion(const char *s) {
 
     free(hour_str);
     free(meridian);
-    free(time_str);
     free(endptr);
     return NULL;
   } else {
@@ -87,7 +85,6 @@ char *HACKERRANK_WARMUP_timeConversion(const char *s) {
   snprintf(conversion, BUFFER_MAX_SIZE, "%02ld%s", hour, time_str);
   free(hour_str);
   free(meridian);
-  free(time_str);
 
   return conversion;
 }