模板——快速傅里叶变换(递归)

#include #include using namespace std; const int N = 1e6 + 10; const double PI = acos(-1); struct Complex { double R, I; Complex() { R = 0, I = 0; } Complex(double r, double i) :R(r), I(i) {} }; Complex operator+(Complex a, Complex b) { return Complex(a.R + b.R, a.I + b.I); } Complex operator-(Co