View Compilation Error

0_0_24101716_23046.cpp: In function 'bool bfs()':
0_0_24101716_23046.cpp:34:34: error: could not convert 'Q.std::queue<_Tp, _Sequence>::emplace<{}>()' from 'void' to 'bool'
                 while(!Q.emplace())
                                  ^
0_0_24101716_23046.cpp:34:34: error: in argument to unary !
0_0_24101716_23046.cpp:44:38: error: could not convert 'Q.std::queue<_Tp, _Sequence>::emplace<{}>()' from 'void' to 'bool'
                     while(!Q.emplace())
                                      ^
0_0_24101716_23046.cpp:44:38: error: in argument to unary !