answer.code: In function ‘main’:
answer.code:47:5: warning: implicit declaration of function ‘quick_sort’ [-Wimplicit-function-declaration]
   47 |     quick_sort(p, 0, n - 1);
      |     ^~~~~~~~~~
answer.code:40:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
   40 |     scanf("%d", &n);
      |     ^~~~~~~~~~~~~~~
answer.code:43:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result]
   43 |         scanf("%d", &p[i].x);
      |         ^~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccLLjbID.o: in function `main':
answer.code:(.text.startup+0xe7): undefined reference to `quick_sort'
collect2: error: ld returned 1 exit status