Mã chấm: 459990

Main.cc: In function ‘int min_height_difference(int*, int)’:
Main.cc:10:36: error: ‘compare’ was not declared in this scope
   10 |     qsort(heights, n, sizeof(int), compare);
      |                                    ^~~~~~~
Main.cc: In function ‘int main()’:
Main.cc:17:10: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   17 |     scanf("%d", &N);
      |     ~~~~~^~~~~~~~~~
Main.cc:22:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   22 |         scanf("%d", &heights[i]);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~