Class Solution
java.lang.Object
g0601_0700.s0675_cut_off_trees_for_golf_event.Solution
675 - Cut Off Trees for Golf Event.<p>Hard</p>
<p>You are asked to cut off all the trees in a forest for a golf event. The forest is represented as an <code>m x n</code> matrix. In this matrix:</p>
<ul>
<li><code>0</code> means the cell cannot be walked through.</li>
<li><code>1</code> represents an empty cell that can be walked through.</li>
<li>A number greater than <code>1</code> represents a tree in a cell that can be walked through, and this number is the tree’s height.</li>
</ul>
<p>In one step, you can walk in any of the four directions: north, east, south, and west. If you are standing in a cell with a tree, you can choose whether to cut it off.</p>
<p>You must cut off the trees in order from shortest to tallest. When you cut off a tree, the value at its cell becomes <code>1</code> (an empty cell).</p>
<p>Starting from the point <code>(0, 0)</code>, return <em>the minimum steps you need to walk to cut off all the trees</em>. If you cannot cut off all the trees, return <code>-1</code>.</p>
<p>You are guaranteed that no two trees have the same height, and there is at least one tree needs to be cut off.</p>
<p><strong>Example 1:</strong></p>
<p><img src="https://assets.leetcode.com/uploads/2020/11/26/trees1.jpg" alt="" /></p>
<p><strong>Input:</strong> forest = [[1,2,3],[0,0,4],[7,6,5]]</p>
<p><strong>Output:</strong> 6</p>
<p><strong>Explanation:</strong> Following the path above allows you to cut off the trees from shortest to tallest in 6 steps.</p>
<p><strong>Example 2:</strong></p>
<p><img src="https://assets.leetcode.com/uploads/2020/11/26/trees2.jpg" alt="" /></p>
<p><strong>Input:</strong> forest = [[1,2,3],[0,0,0],[7,6,5]]</p>
<p><strong>Output:</strong> -1</p>
<p><strong>Explanation:</strong> The trees in the bottom row cannot be accessed as the middle row is blocked.</p>
<p><strong>Example 3:</strong></p>
<p><strong>Input:</strong> forest = [[2,3,4],[0,0,5],[8,7,6]]</p>
<p><strong>Output:</strong> 6</p>
<p><strong>Explanation:</strong> You can follow the same path as Example 1 to cut off all the trees. Note that you can cut off the first tree at (0, 0) before making any steps.</p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>m == forest.length</code></li>
<li><code>n == forest[i].length</code></li>
<li><code>1 <= m, n <= 50</code></li>
<li><code>0 <= forest[i][j] <= 10<sup>9</sup></code></li>
</ul>
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Constructor Summary
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Method Summary
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Constructor Details
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Solution
public Solution()
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Method Details
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cutOffTree
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