View Compilation Error

0_0_37495757_27921.cpp: In function 'int input()':
0_0_37495757_27921.cpp:8:25: error: 'memset' was not declared in this scope
     memset(a,0,sizeof(a));
                         ^
0_0_37495757_27921.cpp: In function 'int main()':
0_0_37495757_27921.cpp:49:38: error: 'reverse' was not declared in this scope
         reverse(vec.begin(),vec.end());
                                      ^