Compilare: user.cpp: In function ‘void DF(int)’: user.cpp:21:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if( !v[ x]) ^ user.cpp: In function ‘int main()’: user.cpp:31:12: warning: unused variable ‘sol’ [-Wunused-variable] int i, sol = 0, N, x, r; ^ user.cpp:31:24: warning: unused variable ‘x’ [-Wunused-variable] int i, sol = 0, N, x, r; ^ user.cpp:48:11: warning: ‘r’ may be used uninitialized in this function [-Wmaybe-uninitialized] DF( r); ^