View Compilation Error

0_0_21389930_28732.cpp: In function 'void build()':
0_0_21389930_28732.cpp:29:26: error: 'memset' was not declared in this scope
  memset(vis,0,sizeof(vis));
                          ^
0_0_21389930_28732.cpp: In function 'int main()':
0_0_21389930_28732.cpp:54:27: error: 'memset' was not declared in this scope
   memset(sum,0,sizeof(sum));
                           ^