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[leetcode]304. Range Sum Query 2D - Immutable二維區間求和 - 不變

圖片 rectangle 元素 borde ive mat element 技術分享 red

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).

技術分享圖片
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
sumRegion(1, 1, 2, 2) -> 11
sumRegion(1, 2, 2, 4) -> 12

題目

給定元素不變的矩陣,求各種子矩陣和。

思路

代碼

[leetcode]304. Range Sum Query 2D - Immutable二維區間求和 - 不變