View Compilation Error

0_0_13210437_4020.cpp: In function 'int main()':
0_0_13210437_4020.cpp:29:37: error: 'memset' was not declared in this scope
         memset(visit,0,sizeof(visit));
                                     ^
0_0_13210437_4020.cpp:44:27: error: 'sort' was not declared in this scope
         sort(num,num+t,cmp);
                           ^