Compilare: user.cpp: In function ‘int main()’: user.cpp:32:9: warning: unused variable ‘j’ [-Wunused-variable] int i, j, a, b, c, u, v; ^ user.cpp:32:24: warning: unused variable ‘v’ [-Wunused-variable] int i, j, a, b, c, u, v; ^ user.cpp:33:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.in", "r", stdin); ^ user.cpp:34:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.out", "w", stdout); ^ user.cpp:35:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:38:99: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i = 1; i <= m; i++) scanf("%d%d%d", &a, &b, &c), graph[a - 1].push_back(make_pair(b - 1, c));//graph[b-1].push_back(make_pair(a-1, c)); ^