View Compilation Error

0_0_13435145_29894.cpp: In function 'bool BFS(int, int)':
0_0_13435145_29894.cpp:16:32: error: 'memset' was not declared in this scope
     memset(pre, -1, sizeof(pre));
                                ^
0_0_13435145_29894.cpp: In function 'int main()':
0_0_13435145_29894.cpp:57:31: error: 'memset' was not declared in this scope
         memset(r, 0, sizeof(r));
                               ^