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47 lines
2.3 KiB
HTML
47 lines
2.3 KiB
HTML
<p>Design an algorithm that accepts a stream of integers and retrieves the product of the last <code>k</code> integers of the stream.</p>
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<p>Implement the <code>ProductOfNumbers</code> class:</p>
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<ul>
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<li><code>ProductOfNumbers()</code> Initializes the object with an empty stream.</li>
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<li><code>void add(int num)</code> Appends the integer <code>num</code> to the stream.</li>
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<li><code>int getProduct(int k)</code> Returns the product of the last <code>k</code> numbers in the current list. You can assume that always the current list has at least <code>k</code> numbers.</li>
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</ul>
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<p>The test cases are generated so that, at any time, the product of any contiguous sequence of numbers will fit into a single 32-bit integer without overflowing.</p>
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<p> </p>
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<p><strong>Example:</strong></p>
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<pre>
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<strong>Input</strong>
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["ProductOfNumbers","add","add","add","add","add","getProduct","getProduct","getProduct","add","getProduct"]
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[[],[3],[0],[2],[5],[4],[2],[3],[4],[8],[2]]
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<strong>Output</strong>
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[null,null,null,null,null,null,20,40,0,null,32]
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<strong>Explanation</strong>
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ProductOfNumbers productOfNumbers = new ProductOfNumbers();
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productOfNumbers.add(3); // [3]
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productOfNumbers.add(0); // [3,0]
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productOfNumbers.add(2); // [3,0,2]
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productOfNumbers.add(5); // [3,0,2,5]
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productOfNumbers.add(4); // [3,0,2,5,4]
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productOfNumbers.getProduct(2); // return 20. The product of the last 2 numbers is 5 * 4 = 20
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productOfNumbers.getProduct(3); // return 40. The product of the last 3 numbers is 2 * 5 * 4 = 40
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productOfNumbers.getProduct(4); // return 0. The product of the last 4 numbers is 0 * 2 * 5 * 4 = 0
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productOfNumbers.add(8); // [3,0,2,5,4,8]
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productOfNumbers.getProduct(2); // return 32. The product of the last 2 numbers is 4 * 8 = 32
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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>0 <= num <= 100</code></li>
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<li><code>1 <= k <= 4 * 10<sup>4</sup></code></li>
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<li>At most <code>4 * 10<sup>4</sup></code> calls will be made to <code>add</code> and <code>getProduct</code>.</li>
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<li>The product of the stream at any point in time will fit in a <strong>32-bit</strong> integer.</li>
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</ul>
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