View Compilation Error

0_0_23968207_17045.cpp: In function 'void dijkstra(int)':
0_0_23968207_17045.cpp:39:29: error: 'memset' was not declared in this scope
     memset(vis,0,sizeof(vis));
                             ^
0_0_23968207_17045.cpp: In function 'int main()':
0_0_23968207_17045.cpp:70:36: error: 'memset' was not declared in this scope
         memset(head,-1,sizeof(head));
                                    ^