Compilare: main.cpp: In function 'void dijkstra(int)': main.cpp:24:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < gr[node].size(); i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:66:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("tollroads.in", "r", stdin); ^ main.cpp:67:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("tollroads.out", "w", stdout); ^ main.cpp:76:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x, &y); ^ main.cpp: In function 'char advance()': main.cpp:42:34: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buffer, 1, SIZE, stdin); ^