c_cpp 设计一个类来处理矩阵，它需要能够返回ma中任意子矩形元素的平均值

Posted 2021-05-14

class matrix {
	private:
		int value[MAX_ROW][MAX_COL];
		int sum[MAX_ROW][MAX_COL];
		int row, col;
	public:
		void calc_sum() {
			for(int r=0; r<=row; r++) sum[r][0] = 0;
			for(int c=0; c<=col; c++) sum[0][c] = 0;
			for(int r=1; r<=row; r++)
				for(int c=1; c<=col; c++)
					sum[r][c] = value[r][c] + sum[r-1][c] +
					  sum[r][c-1] - sum[r-1][c-1];

		}
		double calc_avg(int r1, int c1, int r2, int c2) {
			double s = sum[r2][c2] + sum[r1-1][c1-1]
			  			- sum[r1-1][c2] - sum[r2][c1-1];
			int total_num = (r2 - r1 + 1) * (c2 - c1 + 1);
			return s / total_num;
		}
};