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49 lines
2.3 KiB
HTML
49 lines
2.3 KiB
HTML
<p>You are given a <b>0-index</b><strong>ed</strong> string <code>street</code>. Each character in <code>street</code> is either <code>'H'</code> representing a house or <code>'.'</code> representing an empty space.</p>
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<p>You can place buckets on the <strong>empty spaces</strong> to collect rainwater that falls from the adjacent houses. The rainwater from a house at index <code>i</code> is collected if a bucket is placed at index <code>i - 1</code> <strong>and/or</strong> index <code>i + 1</code>. A single bucket, if placed adjacent to two houses, can collect the rainwater from <strong>both</strong> houses.</p>
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<p>Return <em>the <strong>minimum </strong>number of buckets needed so that for <strong>every</strong> house, there is <strong>at least</strong> one bucket collecting rainwater from it, or </em><code>-1</code><em> if it is impossible.</em></p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> street = "H..H"
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<strong>Output:</strong> 2
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<strong>Explanation:</strong>
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We can put buckets at index 1 and index 2.
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"H..H" -> "HBBH" ('B' denotes where a bucket is placed).
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The house at index 0 has a bucket to its right, and the house at index 3 has a bucket to its left.
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Thus, for every house, there is at least one bucket collecting rainwater from it.
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</pre>
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<p><strong>Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> street = ".H.H."
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<strong>Output:</strong> 1
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<strong>Explanation:</strong>
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We can put a bucket at index 2.
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".H.H." -> ".HBH." ('B' denotes where a bucket is placed).
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The house at index 1 has a bucket to its right, and the house at index 3 has a bucket to its left.
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Thus, for every house, there is at least one bucket collecting rainwater from it.
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</pre>
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<p><strong>Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> street = ".HHH."
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<strong>Output:</strong> -1
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<strong>Explanation:</strong>
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There is no empty space to place a bucket to collect the rainwater from the house at index 2.
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Thus, it is impossible to collect the rainwater from all the houses.
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= street.length <= 10<sup>5</sup></code></li>
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<li><code>street[i]</code> is either<code>'H'</code> or <code>'.'</code>.</li>
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</ul>
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