View Compilation Error

0_0_21939565_18582.cpp: In function 'void Dijkstra(long long int)':
0_0_21939565_18582.cpp:40:32: error: 'memset' was not declared in this scope
  memset(vis, false, sizeof(vis));
                                ^
0_0_21939565_18582.cpp: In function 'int main()':
0_0_21939565_18582.cpp:74:32: error: 'memset' was not declared in this scope
   memset(head, -1, sizeof(head));
                                ^