Compilare: main.cpp: In function 'int dijkstra()': main.cpp:67:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < G[u].size() ; i ++) ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:95:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("smen.in" , "r" , stdin); ^ main.cpp:96:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("smen.out" , "w" , stdout); ^ main.cpp:98:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d" , &n , &k , &a , &b); ^ main.cpp:102:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &v[i]); ^