Compilare: user.cpp: In function ‘void update_hash(int)’: user.cpp:21:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<h[k].size() && ok==0; i++) ^ user.cpp: In function ‘void delete_hash(int)’: user.cpp:34:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<h[k].size(); i++) ^ user.cpp:37:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i!=h[k].size()-1) ^ user.cpp:36:11: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(h[k][i]==x) ^ user.cpp: In function ‘int query_hash(int)’: user.cpp:48:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<h[k].size(); i++) ^ user.cpp:47:9: warning: unused variable ‘ok’ [-Wunused-variable] int ok=0; ^