View Compilation Error

0_0_20980000_6585.cpp: In function 'bool bfs()':
0_0_20980000_6585.cpp:39:30: error: 'memset' was not declared in this scope
     memset(dis,-1,sizeof(dis));
                              ^
0_0_20980000_6585.cpp: In function 'int main()':
0_0_20980000_6585.cpp:89:36: error: 'memset' was not declared in this scope
         memset(head,-1,sizeof(head));
                                    ^