View Compilation Error

0_0_31182509_9244.cpp: In function 'void bfs(long long int)':
0_0_31182509_9244.cpp:19:38: error: 'memset' was not declared in this scope
     memset(pre, 0, sizeof(LL) * (n+2));
                                      ^
0_0_31182509_9244.cpp: In function 'long long int KM()':
0_0_31182509_9244.cpp:38:35: error: 'memset' was not declared in this scope
     memset(lx, 0, sizeof(LL)*(n+2));
                                   ^