矩阵乘法

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1010;

int n, m;
int x, y;
int res[N][N];
int a[N][N], b[N][N];

int main()
{
    cin >> n >> m;


    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= m; j ++ )
            cin >> a[i][j];

    cin >> x >> y;      

    for (int i = 1; i <= x; i ++ )
        for (int j = 1; j <= y; j ++ )
            cin >> b[i][j];

    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= y; j ++ )
            for (int k = 1; k <= m; k ++ )
                res[i][j] += a[i][k] * b[k][j];

    for (int i = 1; i <= n; i ++ )
    {
        for (int j = 1; j <= y; j ++ )
            cout << res[i][j] << ' ';
        puts("");
    }

    return 0;
}