Compilare: user.c: In function ‘add_edge’: user.c:80:21: warning: implicit declaration of function ‘realloc’ [-Wimplicit-function-declaration] leftOut[left] = realloc(leftOut[left], (last + 1) * sizeof(int)); ^~~~~~~ user.c:80:21: warning: incompatible implicit declaration of built-in function ‘realloc’ user.c:80:21: note: include ‘<stdlib.h>’ or provide a declaration of ‘realloc’ user.c: In function ‘main’: user.c:185:29: warning: incompatible implicit declaration of built-in function ‘realloc’ leftOut[left] = realloc(leftOut[left], 0); ^~~~~~~ user.c:185:29: note: include ‘<stdlib.h>’ or provide a declaration of ‘realloc’ user.c:121:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("caroiaj.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:122:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("caroiaj.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:124:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &t); ^~~~~~~~~~~~~~~ user.c:127:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &n); ^~~~~~~~~~~~~~~ user.c:134:17: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &value); ^~~~~~~~~~~~~~~~~~~