题目描述：
Given a 2D matrix, find the sum of the elements inside the rectangle defined by (row1, col1), (row2, col2).
The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, col2) = (4 ...
Given a 2D matrix, find the sum of the elements inside the rectangle defined by (row1, col1), (row2, col2).
The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, col2) = (4 ...