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51 lines
2.4 KiB
HTML
51 lines
2.4 KiB
HTML
<p>Given an <strong>empty</strong> set of intervals, implement a data structure that can:</p>
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<ul>
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<li><strong>Add</strong> an interval to the set of intervals.</li>
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<li><strong>Count</strong> the number of integers that are present in <strong>at least one</strong> interval.</li>
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</ul>
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<p>Implement the <code>CountIntervals</code> class:</p>
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<ul>
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<li><code>CountIntervals()</code> Initializes the object with an empty set of intervals.</li>
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<li><code>void add(int left, int right)</code> Adds the interval <code>[left, right]</code> to the set of intervals.</li>
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<li><code>int count()</code> Returns the number of integers that are present in <strong>at least one</strong> interval.</li>
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</ul>
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<p><strong>Note</strong> that an interval <code>[left, right]</code> denotes all the integers <code>x</code> where <code>left <= x <= right</code>.</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>
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["CountIntervals", "add", "add", "count", "add", "count"]
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[[], [2, 3], [7, 10], [], [5, 8], []]
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<strong>Output</strong>
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[null, null, null, 6, null, 8]
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<strong>Explanation</strong>
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CountIntervals countIntervals = new CountIntervals(); // initialize the object with an empty set of intervals.
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countIntervals.add(2, 3); // add [2, 3] to the set of intervals.
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countIntervals.add(7, 10); // add [7, 10] to the set of intervals.
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countIntervals.count(); // return 6
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// the integers 2 and 3 are present in the interval [2, 3].
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// the integers 7, 8, 9, and 10 are present in the interval [7, 10].
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countIntervals.add(5, 8); // add [5, 8] to the set of intervals.
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countIntervals.count(); // return 8
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// the integers 2 and 3 are present in the interval [2, 3].
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// the integers 5 and 6 are present in the interval [5, 8].
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// the integers 7 and 8 are present in the intervals [5, 8] and [7, 10].
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// the integers 9 and 10 are present in the interval [7, 10].
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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 <= left <= right <= 10<sup>9</sup></code></li>
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<li>At most <code>10<sup>5</sup></code> calls <strong>in total</strong> will be made to <code>add</code> and <code>count</code>.</li>
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<li>At least <strong>one</strong> call will be made to <code>count</code>.</li>
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</ul>
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