Aiiage Camp Day3 G Gatehouse

题意

　　求↓

　　

　　op是异或。

　　n=2^k, 1<=k<=17

题解

　　FWT裸题..甚至在题面告知了模板名..

#include <bits/stdc++.h>
using namespace std;

void FWT(long long a[], int n)
{
    for (int d = 1; d < n; d <<= 1)
        for (int m = d << 1, i = 0; i < n; i += m)
            for (int j = 0; j < d; ++j)
            {
                long long x = a[i + j], y = a[i + j + d];
                a[i + j] = x + y; 
            }
}

void UFWT(long long a[], int n)
{
    for (int d = 1; d < n; d <<= 1)
        for (int m = d << 1, i = 0; i < n; i += m)
            for (int j = 0; j < d; ++j)
            {
                long long x = a[i + j], y = a[i + j + d];
                a[i + j] = x - y; 
            }
}

long long a[200000], b[200000];

int main()
{
    int k;
    scanf("%d", &k);
    int n = pow(2, k);
    for (int i = 0; i < n; ++i)
        scanf("%lld", a + i);
    for (int i = 0; i < n; ++i)
        scanf("%lld", b + i);
    FWT(a, n);
    FWT(b, n);
    for (int i = 0; i < n; ++i)
        a[i] = a[i] * b[i];
    UFWT(a, n);
    for (int i = 0; i < n; ++i)
        printf("%lld
", a[i]);
    
    return 0;
}