Package g2201_2300.s2257_count_unguarded_cells_in_the_grid

Class Solution

java.lang.Object

g2201_2300.s2257_count_unguarded_cells_in_the_grid.Solution

public class Solution
extends Object

2257 - Count Unguarded Cells in the Grid.<p>Medium</p> <p>You are given two integers <code>m</code> and <code>n</code> representing a <strong>0-indexed</strong> <code>m x n</code> grid. You are also given two 2D integer arrays <code>guards</code> and <code>walls</code> where <code>guards[i] = [row_i, col_i]</code> and <code>walls[j] = [row_j, col_j]</code> represent the positions of the <code>i^th</code> guard and <code>j^th</code> wall respectively.</p> <p>A guard can see <strong>every</strong> cell in the four cardinal directions (north, east, south, or west) starting from their position unless <strong>obstructed</strong> by a wall or another guard. A cell is <strong>guarded</strong> if there is <strong>at least</strong> one guard that can see it.</p> <p>Return <em>the number of unoccupied cells that are <strong>not</strong> <strong>guarded</strong>.</em></p> <p><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2022/03/10/example1drawio2.png" alt="" /></p> <p><strong>Input:</strong> m = 4, n = 6, guards = [[0,0],[1,1],[2,3]], walls = [[0,1],[2,2],[1,4]]</p> <p><strong>Output:</strong> 7</p> <p><strong>Explanation:</strong> The guarded and unguarded cells are shown in red and green respectively in the above diagram. There are a total of 7 unguarded cells, so we return 7.</p> <p><strong>Example 2:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2022/03/10/example2drawio.png" alt="" /></p> <p><strong>Input:</strong> m = 3, n = 3, guards = [[1,1]], walls = [[0,1],[1,0],[2,1],[1,2]]</p> <p><strong>Output:</strong> 4</p> <p><strong>Explanation:</strong> The unguarded cells are shown in green in the above diagram. There are a total of 4 unguarded cells, so we return 4.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= m, n <= 10⁵</code></li> <li><code>2 <= m * n <= 10⁵</code></li> <li><code>1 <= guards.length, walls.length <= 5 * 10⁴</code></li> <li><code>2 <= guards.length + walls.length <= m * n</code></li> <li><code>guards[i].length == walls[j].length == 2</code></li> <li><code>0 <= row_i, row_j < m</code></li> <li><code>0 <= col_i, col_j < n</code></li> <li>All the positions in <code>guards</code> and <code>walls</code> are <strong>unique</strong>.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	countUnguarded(int m, int n, int[][] guards, int[][] walls)

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

countUnguarded

public int countUnguarded(int m,
 int n,
 int[][] guards,
 int[][] walls)