题解 | #矩阵乘法#

public class Main {
    public static void main(String []args) {
        Scanner in = new Scanner(System.in);
        int m1 = Integer.parseInt(in.nextLine());
        int n = Integer.parseInt(in.nextLine());
        int m2 = Integer.parseInt(in.nextLine());

        int [][] a = new int[m1][n];
        int [][] b = new int[n][m2];
        for (int  i = 0; i < m1; i++) {
            String []strs = in.nextLine().split(" ");
            for (int j = 0; j < n; j++) {
                a[i][j] = Integer.parseInt(strs[j]);
            }
        }
        for (int  i = 0; i < n; i++) {
            String []strs = in.nextLine().split(" ");
            for (int j = 0; j < m2; j++) {
                b[i][j] = Integer.parseInt(strs[j]);
            }
        }
        int[][] c = new int[m1][m2];
        ArrayList<Integer> res = new ArrayList();
        for (int i = 0; i < m1; i++) {
            
            int index = 0;
            while (index < m2) {
                int sum = 0;
                for (int j = 0; j < n; j++) {
                    sum += a[i][j] * b[j][index];
                }
                index++;
                res.add(sum);
            }
        }
        for (int i = 0; i < res.size(); i++) {
            if (i % m2 == 0 && i > 0) {
                System.out.println();
            }
            System.out.print(res.get(i) + " ");
        }
    }
}