How to Solve Number of Black Blocks Problem
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Number of Black Blocks
You are given two integers m and n representing the dimensions of a 0-indexed m x n grid. You are also given a 0-indexed 2D integer matrix coordinates, where coordinates[i] = [x, y] indicates that the...
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Understanding the Number of Black Blocks Problem
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Problem Statement
You are given two integers m and n representing the dimensions of a 0-indexed m x n grid. You are also given a 0-indexed 2D integer matrix coordinates, where coordinates[i] = [x, y] indicates that the cell with coordinates [x, y] is colored black. All cells in the grid that do not appear in coordinates are white. A block is defined as a 2 x 2 submatrix of the grid. More formally, a block with cell [x, y] as its top-left corner where 0 <= x < m - 1 and 0 <= y < n - 1 contains the coordinates [x, y], [x + 1, y], [x, y + 1], and [x + 1, y + 1]. Return a 0-indexed integer array arr of size 5 such that arr[i] is the number of blocks that contains exactly i black cells.
Number of Black Blocks
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Examples
m = 3, n = 3, coordinates = [[0,0]][3,1,0,0,0]The grid looks like this: There is only 1 block with one black cell, and it is the block starting with cell [0,0]. The other 3 blocks start with cells [0,1], [1,0] and [1,1]. They all have zero black cells. Thus, we return [3,1,0,0,0].
m = 3, n = 3, coordinates = [[0,0],[1,1],[0,2]][0,2,2,0,0]The grid looks like this: There are 2 blocks with two black cells (the ones starting with cell coordinates [0,0] and [0,1]). The other 2 blocks have starting cell coordinates of [1,0] and [1,1]. They both have 1 black cell. Therefore, we return [0,2,2,0,0].
Constraints
2 <= m <= 1052 <= n <= 1050 <= coordinates.length <= 104coordinates[i].length == 20 <= coordinates[i][0] < m0 <= coordinates[i][1] < nIt is guaranteed that coordinates contains pairwise distinct coordinates.How Interview Coder Helps with Leetcode Problems
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