View Compilation Error

0_0_27600705_8434.cpp: In function 'int main()':
0_0_27600705_8434.cpp:23:35: error: 'memset' was not declared in this scope
   memset(G, 0, sizeof(int) * N * N);
                                   ^
0_0_27600705_8434.cpp: In function 'bool BFS(int, int)':
0_0_27600705_8434.cpp:55:33: error: 'memset' was not declared in this scope
  memset(pre, -1, sizeof(int) * n);
                                 ^