View Compilation Error

0_0_17719204_7903.cpp: In function 'void FFT::FFT(FFT::comp*, int, int)':
0_0_17719204_7903.cpp:25:25: error: 'swap' was not declared in this scope
     swap(a[i], a[pos[i]]);
                         ^
0_0_17719204_7903.cpp: In function 'int main()':
0_0_17719204_7903.cpp:101:26: error: 'memset' was not declared in this scope
   memset(dp, 0, sizeof dp);
                          ^