View Compilation Error

0_0_15791646_16983.cpp: In function 'int main()':
0_0_15791646_16983.cpp:22:25: error: 'memset' was not declared in this scope
   memset(a, 0, sizeof(a));
                         ^
0_0_15791646_16983.cpp:27:21: error: 'sort' was not declared in this scope
   sort(a, a + t, cmp);
                     ^