题解 | #矩阵乘法#

#include <iostream>
#include <vector>
using namespace std;

int compute_one(vector<int>& M1, vector<int>& M2) {
    int l = M1.size();
    int res = 0;
    for (int i = 0; i < l; i++) {
        res += M1[i] * M2[i];
    }
    return res;
}

int main() {
    int h, c, z;
    cin >> h >> c >> z;
    vector<vector<int>> M1(h, vector<int>(c));
    vector<vector<int>> M2(z, vector<int>(c));
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < c; j++) {
            cin >> M1[i][j];
        }
    }

    for (int i = 0; i < c; i++) {
        for (int j = 0; j < z; j++) {
            cin >> M2[j][i];
        }
    }
    /*
    for (auto l : M1) {
        for (auto a : l) {
            cout << a << ' ';
        }
        cout << endl;
    }
    for (auto l : M2) {
        for (auto a : l) {
            cout << a << ' ';
        }
        cout << endl;
    }
    */

    vector<vector<int>> res(h, vector<int>(z));
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < z; j++) {
            res[i][j] = compute_one(M1[i], M2[j]);
        }
    }
    for (auto l : res) {
        for (auto a : l) {
            cout << a << ' ';
        }
        cout << endl;
    }

}
// 64 位输出请用 printf("%lld")

把第二个矩阵重新排列一下