Compilare: main.cpp: In member function 'int AVL::cel_mai_mic_mai_mare(int, nod*)': main.cpp:225:20: warning: converting to non-pointer type 'int' from NULL [-Wconversion-null] return NULL; ^~~~ main.cpp: In member function 'int AVL::cel_mai_mare_mai_mic(int, nod*)': main.cpp:265:20: warning: converting to non-pointer type 'int' from NULL [-Wconversion-null] return NULL; ^~~~