/in/foo.c: In function 'add_edge':
/in/foo.c:25:20: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
     new_edge->next = graph[u].head;
                    ^
/in/foo.c: In function 'dijkstra':
/in/foo.c:53:61: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
         for (Edge* edge = graph[u].head; edge != NULL; edge = edge->next) {
                                                             ^
/in/foo.c: In function 'free_graph':
/in/foo.c:68:21: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
             current = current->next;
                     ^
/in/foo.c: In function 'main':
/in/foo.c:65:15: warning: iteration 999 invokes undefined behavior [-Waggressive-loop-optimizations]
         Edge* current = graph[i].head;
               ^~~~~~~
/in/foo.c:64:5: note: within this loop
     for (int i = 1; i <= n; i++) {
     ^~~