luk.cpp:11:1: error: invalid use of template-name 'std::set' without an argument list
set visited;
^~~
luk.cpp:11:1: note: class template argument deduction is only available with -std=c++1z or -std=gnu++1z
In file included from /usr/include/c++/7/set:61:0,
from luk.cpp:6:
/usr/include/c++/7/bits/stl_set.h:93:11: note: 'template<class _Key, class _Compare, class _Alloc> class std::set' declared here
class set
^~~
luk.cpp: In function 'int canHandle(int, int)':
luk.cpp:16:5: error: 'visited' was not declared in this scope
visited.insert(v);
^~~~~~~
luk.cpp:18:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i = 0; i < graph[v].size(); i++) {
~~^~~~~~~~~~~~~~~~~
luk.cpp: In function 'int main()':
luk.cpp:46:9: error: 'visited' was not declared in this scope
visited.clear();
^~~~~~~
luk.cpp:29:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
~~~~~^~~~~~~~~~
luk.cpp:34:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &a, &b);
~~~~~^~~~~~~~~~~~~~~~~