Compilare: user.cpp: In function ‘std::vector<int> bfs(int, std::vector<int>&)’: user.cpp:129:9: warning: unused variable ‘start’ [-Wunused-variable] int start = node, end = -1; ^ user.cpp: In function ‘void solve()’: user.cpp:180:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path.size(); ++i) { ^ user.cpp:188:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path.size(); ++i) { ^ user.cpp:192:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path2.size(); ++i) { ^ user.cpp:197:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path.size(); ++i) { ^ user.cpp:200:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path2.size(); ++i) { ^ user.cpp:205:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path.size(); ++i) { ^ user.cpp:211:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < path.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:254:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("puzzle2.in", "r", stdin); ^ user.cpp:255:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:259:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x, &y); ^ user.cpp: In function ‘void solve2()’: user.cpp:102:30: warning: ‘start’ may be used uninitialized in this function [-Wmaybe-uninitialized] if (G[i].size() == 1 && i != start) { ^ user.cpp:121:13: warning: ‘end’ may be used uninitialized in this function [-Wmaybe-uninitialized] fout << end << '\n'; ^