|
| 1 | +<h2><a href="https://leetcode.com/problems/find-the-safest-path-in-a-grid">2812. Find the Safest Path in a Grid</a></h2><h3>Medium</h3><hr><p>You are given a <strong>0-indexed</strong> 2D matrix <code>grid</code> of size <code>n x n</code>, where <code>(r, c)</code> represents:</p> |
| 2 | + |
| 3 | +<ul> |
| 4 | + <li>A cell containing a thief if <code>grid[r][c] = 1</code></li> |
| 5 | + <li>An empty cell if <code>grid[r][c] = 0</code></li> |
| 6 | +</ul> |
| 7 | + |
| 8 | +<p>You are initially positioned at cell <code>(0, 0)</code>. In one move, you can move to any adjacent cell in the grid, including cells containing thieves.</p> |
| 9 | + |
| 10 | +<p>The <strong>safeness factor</strong> of a path on the grid is defined as the <strong>minimum</strong> manhattan distance from any cell in the path to any thief in the grid.</p> |
| 11 | + |
| 12 | +<p>Return <em>the <strong>maximum safeness factor</strong> of all paths leading to cell </em><code>(n - 1, n - 1)</code><em>.</em></p> |
| 13 | + |
| 14 | +<p>An <strong>adjacent</strong> cell of cell <code>(r, c)</code>, is one of the cells <code>(r, c + 1)</code>, <code>(r, c - 1)</code>, <code>(r + 1, c)</code> and <code>(r - 1, c)</code> if it exists.</p> |
| 15 | + |
| 16 | +<p>The <strong>Manhattan distance</strong> between two cells <code>(a, b)</code> and <code>(x, y)</code> is equal to <code>|a - x| + |b - y|</code>, where <code>|val|</code> denotes the absolute value of val.</p> |
| 17 | + |
| 18 | +<p> </p> |
| 19 | +<p><strong class="example">Example 1:</strong></p> |
| 20 | +<img alt="" src="https://assets.leetcode.com/uploads/2023/07/02/example1.png" style="width: 362px; height: 242px;" /> |
| 21 | +<pre> |
| 22 | +<strong>Input:</strong> grid = [[1,0,0],[0,0,0],[0,0,1]] |
| 23 | +<strong>Output:</strong> 0 |
| 24 | +<strong>Explanation:</strong> All paths from (0, 0) to (n - 1, n - 1) go through the thieves in cells (0, 0) and (n - 1, n - 1). |
| 25 | +</pre> |
| 26 | + |
| 27 | +<p><strong class="example">Example 2:</strong></p> |
| 28 | +<img alt="" src="https://assets.leetcode.com/uploads/2023/07/02/example2.png" style="width: 362px; height: 242px;" /> |
| 29 | +<pre> |
| 30 | +<strong>Input:</strong> grid = [[0,0,1],[0,0,0],[0,0,0]] |
| 31 | +<strong>Output:</strong> 2 |
| 32 | +<strong>Explanation:</strong> The path depicted in the picture above has a safeness factor of 2 since: |
| 33 | +- The closest cell of the path to the thief at cell (0, 2) is cell (0, 0). The distance between them is | 0 - 0 | + | 0 - 2 | = 2. |
| 34 | +It can be shown that there are no other paths with a higher safeness factor. |
| 35 | +</pre> |
| 36 | + |
| 37 | +<p><strong class="example">Example 3:</strong></p> |
| 38 | +<img alt="" src="https://assets.leetcode.com/uploads/2023/07/02/example3.png" style="width: 362px; height: 242px;" /> |
| 39 | +<pre> |
| 40 | +<strong>Input:</strong> grid = [[0,0,0,1],[0,0,0,0],[0,0,0,0],[1,0,0,0]] |
| 41 | +<strong>Output:</strong> 2 |
| 42 | +<strong>Explanation:</strong> The path depicted in the picture above has a safeness factor of 2 since: |
| 43 | +- The closest cell of the path to the thief at cell (0, 3) is cell (1, 2). The distance between them is | 0 - 1 | + | 3 - 2 | = 2. |
| 44 | +- The closest cell of the path to the thief at cell (3, 0) is cell (3, 2). The distance between them is | 3 - 3 | + | 0 - 2 | = 2. |
| 45 | +It can be shown that there are no other paths with a higher safeness factor. |
| 46 | +</pre> |
| 47 | + |
| 48 | +<p> </p> |
| 49 | +<p><strong>Constraints:</strong></p> |
| 50 | + |
| 51 | +<ul> |
| 52 | + <li><code>1 <= grid.length == n <= 400</code></li> |
| 53 | + <li><code>grid[i].length == n</code></li> |
| 54 | + <li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li> |
| 55 | + <li>There is at least one thief in the <code>grid</code>.</li> |
| 56 | +</ul> |
0 commit comments