View Compilation Error

0_0_27709521_30095.cpp: In member function 'void Graph::init(int, int, int)':
0_0_27709521_30095.cpp:24:32: error: 'memset' was not declared in this scope
   memset(Head, -1, sizeof(Head));
                                ^
0_0_27709521_30095.cpp: In member function 'int Graph::bfs()':
0_0_27709521_30095.cpp:67:33: error: 'memset' was not declared in this scope
   memset(Depth, 0, sizeof(Depth));
                                 ^