/in/foo.cc: In function 'void spfa(int)':
/in/foo.cc:21:32: error: 'memset' was not declared in this scope
  memset(&inf, 0x3f, sizeof(inf));
                                ^
/in/foo.cc:33:25: error: 'weight' was not declared in this scope
    if(dis[v] > dis[u] + weight){
                         ^~~~~~
/in/foo.cc:32:22: warning: unused variable 'w' [-Wunused-variable]
    int v = es[i].to, w = es[i].weight;
                      ^