Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2). ? ?The above rectangle (with the red border) is defined by (row1, col1) = (2, 1) and (row2, col2) = (4, 3), which contains sum = 8. Example:? Given matrix = [ [3, 0, 1, 4, 2], [5, 6, 3, 2, 1], [1, 2, 0, 1, 5], [4, 1, 0, 1, 7], [1, 0, 3, 0, 5] ] sumRegion(2, 1, 4, 3) -> 8 update(3, 2, 2) sumRegion(2, 1, 4, 3) -> 10 https://leetcode.com/problems/range-sum-query-2d-mutable/discuss/75863/Segment-Tree-Solution-in-Java
308. Range Sum Query 2D - Mutable
原文：https://www.cnblogs.com/tobeabetterpig/p/9913059.html