csp202305-2 矩阵运算

 

优化方法：先k*v，再q*k。（先q*k：n*d×d*n=n*n，改为先k*v：d*n×n*d=d*d，此题d远比n小，所以优化可行）。

 

#include 
using namespace std;
typedef long long int ll;
const ll maxn = 10005;
ll q[maxn][25];
ll k[25][maxn];
ll v[maxn][25];
ll w[maxn];
ll n, d;
ll kv[25][25];
ll ww[maxn][25];
int main()
{
    cin >> n >> d;
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            cin >> q[i][j];
        }
    }
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            cin >> k[j][i];//k转置
        }
    }
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            cin >> v[i][j];
        }
    }
    for (ll i = 1; i <= n; i++)
    {
        cin >> w[i];
    }
    // k*v
    ll ans = 0;
    for (ll i = 1; i <= d; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            for (ll kk = 1; kk <= n; kk++)
            {
                ans += k[i][kk] * v[kk][j];
            }
            kv[i][j] = ans;
            ans = 0;
        }
    }
    
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            for (ll kk = 1; kk <= d; kk++)
            {
                ans += q[i][kk] * kv[kk][j];
            }
            ww[i][j] = ans;
            ans = 0;
        }
    }
    for (ll i = 1; i <= n; i++)
    {
        for (ll j = 1; j <= d; j++)
        {
            ww[i][j] *= w[i];
            cout << ww[i][j] << " ";
        }
        cout << "\n";
    }
}