题解 | 矩阵乘法

class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param a int整型vector<vector<>> 第一个矩阵
     * @param b int整型vector<vector<>> 第二个矩阵
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > solve(vector<vector<int> >& a, vector<vector<int> >& b) {
        int row_a = a.size();
        int col_a_row_b = a[0].size();
        int col_b = b[0].size();

        vector< vector<int>> ans(a.size(), vector<int>(b[0].size(), 0));
        for (int i = 0; i < row_a; i++) {  //a的每一行
            for (int j = 0; j < col_b; j++) {   //b的每一列
                int t = 0;
                for (int w = 0; w < col_a_row_b; w++) {  //向量每个相乘
                    t += a[i][w] * b[w][j];
                }
                ans[i][j] = t;
            }
        }

        return ans;
    }
};