题目大意：给你两个多项式$A,B$，求多项式$C$使得：

$$

C_n=\sum\limits_{x\oplus y=n}A_xB_y

$$

题解：$FWT$

卡点：无

C++ Code：

#include 
     
      #include 
      
       namespace __IO {	int ch;	inline int read() {		while (isspace(ch = getchar())) ;		return ch & 15;	}}using __IO::read;#define maxn 2097152int lim;inline void init(const int n) {	lim = 1; while (lim < n) lim <<= 1;}inline void FWT(long long *A, const int op = 1) {	for (register int mid = 1; mid < lim; mid <<= 1)		for (register int i = 0; i < lim; i += mid << 1)			for (register int j = 0; j < mid; ++j) {				const long long X = A[i + j], Y = A[i + j + mid];				A[i + j] = X + Y, A[i + j + mid] = X - Y;			}	if (!op) for (long long *i = A; i != A + lim; ++i) *i /= lim;}int n;long long A[maxn], B[maxn];int main() {	scanf("%d", &n);	for (int i = 0; i < n; ++i) A[i] = read();	for (int i = 0; i < n; ++i) B[i] = read();	init(n + n);	FWT(A), FWT(B);	for (int i = 0; i < lim; ++i) A[i] = A[i] * B[i];	FWT(A, 0);	for (int i = 0; i < n; ++i) printf("%lld ", A[i]); puts("");	return 0;}