Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:11:12: warning: unused variable ‘i’ [-Wunused-variable] int a, i; ^ user.cpp: In function ‘int main()’: user.cpp:50:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<g2[i].size(); j++) ^ user.cpp:54:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=0; k<g2[nr2].size(); k++) ^ user.cpp:56:29: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(!(nr%2==1&&g2[nr2][k]==nr+1||(nr%2==0&&g2[nr2][k]==nr-1))) ^ user.cpp:64:16: warning: ‘elem’ may be used uninitialized in this function [-Wmaybe-uninitialized] dfs(elem,0); ^