Compilare: user.cpp: In function ‘bool backtrack(int, int)’: user.cpp:42:9: warning: unused variable ‘res’ [-Wunused-variable] bool res = backtrack(pos + 1, n); ^~~ user.cpp:44:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: At global scope: user.cpp:9:13: warning: ‘test’ defined but not used [-Wunused-variable] static bool test = false; ^~~~