Package g2701_2800.s2768_number_of_black_blocks

Class Solution

java.lang.Object
g2701_2800.s2768_number_of_black_blocks.Solution
public class Solution extends java.lang.Object
2768 - Number of Black Blocks.

Medium

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.

Example 1:

Input: m = 3, n = 3, coordinates = [[0,0]]

Output: [3,1,0,0,0]

Explanation: 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].

Example 2:

Input: m = 3, n = 3, coordinates = [[0,0],[1,1],[0,2]]

Output: [0,2,2,0,0]

Explanation: 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 <= 105
  • 2 <= n <= 105
  • 0 <= coordinates.length <= 104
  • coordinates[i].length == 2
  • 0 <= coordinates[i][0] < m
  • 0 <= coordinates[i][1] < n
  • It is guaranteed that coordinates contains pairwise distinct coordinates.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    long[]
    countBlackBlocks(int m, int n, int[][] coordinates)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • countBlackBlocks

      public long[] countBlackBlocks(int m, int n, int[][] coordinates)