Package g0801_0900.s0864_shortest_path_to_get_all_keys

Class Solution

java.lang.Object
g0801_0900.s0864_shortest_path_to_get_all_keys.Solution
public class Solution extends Object
864 - Shortest Path to Get All Keys.<p>Hard</p> <p>You are given an <code>m x n</code> grid <code>grid</code> where:</p> <ul> <li><code>'.'</code> is an empty cell.</li> <li><code>'#'</code> is a wall.</li> <li><code>'@'</code> is the starting point.</li> <li>Lowercase letters represent keys.</li> <li>Uppercase letters represent locks.</li> </ul> <p>You start at the starting point and one move consists of walking one space in one of the four cardinal directions. You cannot walk outside the grid, or walk into a wall.</p> <p>If you walk over a key, you can pick it up and you cannot walk over a lock unless you have its corresponding key.</p> <p>For some <code>1 <= k <= 6</code>, there is exactly one lowercase and one uppercase letter of the first <code>k</code> letters of the English alphabet in the grid. This means that there is exactly one key for each lock, and one lock for each key; and also that the letters used to represent the keys and locks were chosen in the same order as the English alphabet.</p> <p>Return <em>the lowest number of moves to acquire all keys</em>. If it is impossible, return <code>-1</code>.</p> <p><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2021/07/23/lc-keys2.jpg" alt="" /></p> <p><strong>Input:</strong> grid = [&ldquo;@.a.#&rdquo;,&ldquo;###.#&rdquo;,&ldquo;b.A.B&rdquo;]</p> <p><strong>Output:</strong> 8</p> <p><strong>Explanation:</strong> Note that the goal is to obtain all the keys not to open all the locks.</p> <p><strong>Example 2:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2021/07/23/lc-key2.jpg" alt="" /></p> <p><strong>Input:</strong> grid = [&ldquo;@..aA&rdquo;,&ldquo;..B#.&rdquo;,&ldquo;&hellip;.b&rdquo;]</p> <p><strong>Output:</strong> 6</p> <p><strong>Example 3:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2021/07/23/lc-keys3.jpg" alt="" /></p> <p><strong>Input:</strong> grid = [&ldquo;@Aa&rdquo;]</p> <p><strong>Output:</strong> -1</p> <p><strong>Constraints:</strong></p> <ul> <li><code>m == grid.length</code></li> <li><code>n == grid[i].length</code></li> <li><code>1 <= m, n <= 30</code></li> <li><code>grid[i][j]</code> is either an English letter, <code>'.'</code>, <code>'#'</code>, or <code>'@'</code>.</li> <li>The number of keys in the grid is in the range <code>[1, 6]</code>.</li> <li>Each key in the grid is <strong>unique</strong>.</li> <li>Each key in the grid has a matching lock.</li> </ul>

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • shortestPathAllKeys

      public int shortestPathAllKeys(String[] stringGrid)