View Compilation Error

0_0_17129787_5658.cpp: In function 'void build(int)':
0_0_17129787_5658.cpp:30:27: error: 'memset' was not declared in this scope
     memset(p, 0, sizeof(p));
                           ^
0_0_17129787_5658.cpp: In function 'int main()':
0_0_17129787_5658.cpp:57:43: error: 'memset' was not declared in this scope
         memset(sum_top, 0, sizeof(sum_top));
                                           ^