View Compilation Error

0_0_21273700_15287.cpp: In function 'void init()':
0_0_21273700_15287.cpp:26:29: error: 'memset' was not declared in this scope
  memset(head,-1,sizeof(head));
                             ^
0_0_21273700_15287.cpp: In function 'int main()':
0_0_21273700_15287.cpp:68:24: error: 'memset' was not declared in this scope
    memset(h,0,sizeof(h));
                        ^