RT，FFT函数照搬之前的模板应该没问题，Complex类也应该没问题。问题大概率出在主函数中。

还有，我输出的结果和样例有相似之处，第一位数都一样，貌似是精度问题？

样例输入：

5
4006373.885184
15375036.435759
1717456.469144
8514941.004912
1410681.345880

样例输出：

-16838672.693
3439.793
7509018.566
4595686.886
10903040.872

我的输出：

-16409907.469
59867.047
7509018.566
4435431.931
10037641.047

代码：

#include <bits/stdc++.h>



#define MAXN 300000



const double PI = acos(-1);



class Complex {
public:
	inline Complex(double x = 0, double y = 0) : x(x), y(y) {}
	
	inline Complex operator + (const Complex &cp) const { return Complex(this->x + cp.x, this->y + cp.y); }
	inline Complex operator - (const Complex &cp) const { return Complex(this->x - cp.x, this->y - cp.y); }
	inline Complex operator * (const Complex &cp) const { return Complex(this->x * cp.x - this->y * cp.y, this->x * cp.y + this->y * cp.x); }
	
	double x, y;
} f[MAXN], g[MAXN], f_[MAXN];



int m = 1, rotate[MAXN];



inline int read() {
	int num = 0, flag = 1;
	
	char ch = getchar();
	while (ch < '0' || ch > '9') {
		if (ch == '-') flag = -1;
		ch = getchar();
	}
	while (ch >= '0' && ch <= '9') {
		num = num * 10 + ch - '0';
		ch = getchar();
	}
	
	return num * flag;
}



inline void FFT(Complex *Fc, int flag) {
	for (register int i = 0; i < m; i++) if (i < rotate[i]) std::swap(Fc[i], Fc[rotate[i]]);
	
	for (register int num = 2; num <= m; num <<= 1) {
		Complex omega_num_flag_one(cos(2 * PI / num), flag * sin(2 * PI / num));
		for (register int i = 0; i < m; i += num) {
			Complex omega_num_i(1, 0);
			for (register int j = i; j < i + (num >> 1); j++) {
				Complex right_value = omega_num_i * Fc[j + (num >> 1)];
				Fc[j + (num >> 1)] = Fc[j] - right_value;
				Fc[j] = Fc[j] + right_value;
				omega_num_i = omega_num_i * omega_num_flag_one;
			}
		}
	}
	
	if (flag == -1) for (register int i = 0; i < m; i++) Fc[i].x /= m;
}



int main() {
	int n = read();
	for (register int i = 1; i <= n; i++) scanf("%lf", &f[i].x), g[i].x = double(1.0 / i / i), f_[n - i].x = f[i].x;
	
	while(m <= n) m <<= 1;
	for (register int i = 0; i < m; i++) rotate[i] = (rotate[i >> 1] >> 1) | (i & 1 ? m >> 1 : 0);
	FFT(f, 1); FFT(g, 1); FFT(f_, 1);
	for (register int i = 0; i < m; i++) f[i] = f[i] * g[i], f_[i] = f_[i] * g[i];
	FFT(f, -1); FFT(f_, -1);
	
	for (register int i = 1; i <= n; i++) printf("%.3lf\n", f[i].x - f_[n - i].x);
	return 0;
}

重复：勿水