Compilare: user.cpp: In function ‘void dfs(int, int&)’: user.cpp:24: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs1(int)’: user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs11(int)’: user.cpp:59: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs2(int)’: user.cpp:76: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:255: warning: suggest explicit braces to avoid ambiguous ‘else’ user.cpp:301: warning: suggest explicit braces to avoid ambiguous ‘else’