View Compilation Error

0_0_21688522_24193.cpp: In function 'void dijkstra(int, LL*)':
0_0_21688522_24193.cpp:7:39: error: 'memset' was not declared in this scope
 #define mest(a,b) memset(a,b,sizeof(a))
                                       ^
0_0_21688522_24193.cpp:35:2: note: in expansion of macro 'mest'
  mest(vis, 0);
  ^
0_0_21688522_24193.cpp: In function 'int main()':
0_0_21688522_24193.cpp:69:31: error: 'memset' was not declared in this scope
   memset(head, 0, sizeof(head));
                               ^