View Compilation Error

0_0_29491570_10587.cpp: In function 'void Trajan()':
0_0_29491570_10587.cpp:192:27: error: 'memset' was not declared in this scope
  memset(dfn,-1,sizeof(dfn));
                           ^
0_0_29491570_10587.cpp: In function 'int main()':
0_0_29491570_10587.cpp:230:29: error: 'memset' was not declared in this scope
   memset(head,0,sizeof(head));
                             ^