View Compilation Error

0_0_33174898_32541.cpp: In function 'void tarjan_init(int)':
0_0_33174898_32541.cpp:61:29: error: 'memset' was not declared in this scope
  memset(DFN, -1, sizeof(DFN));
                             ^
0_0_33174898_32541.cpp: In function 'void init()':
0_0_33174898_32541.cpp:66:42: error: 'memset' was not declared in this scope
 void init(){memset(head, -1, sizeof(head)); edgenum=0;}
                                          ^
0_0_33174898_32541.cpp: In function 'int main()':
0_0_33174898_32541.cpp:81:37: error: 'memset' was not declared in this scope
         memset(inde, 0, sizeof(inde));  
                                     ^