View Compilation Error

0_0_28342959_18136.cpp: In function 'int gefuc_partiparion(int, int)':
0_0_28342959_18136.cpp:13:26: error: 'sqrt' was not declared in this scope
  int k = (sqrt(1 + 24 * n) + 1) / 6 + 1;
                          ^
0_0_28342959_18136.cpp:14:24: error: 'memset' was not declared in this scope
  memset(p, 0, sizeof(p));
                        ^