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51 lines
1.9 KiB
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51 lines
1.9 KiB
HTML
<p>Given an array of functions <code>[f<span style="font-size: 10.8333px;">1</span>, f<sub>2</sub>, f<sub>3</sub>, ..., f<sub>n</sub>]</code>, return a new function <code>fn</code> that is the <strong>function composition</strong> of the array of functions.</p>
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<p>The <strong>function composition</strong> of <code>[f(x), g(x), h(x)]</code> is <code>fn(x) = f(g(h(x)))</code>.</p>
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<p>The <strong>function composition</strong> of an empty list of functions is the <strong>identity function</strong> <code>f(x) = x</code>.</p>
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<p>You may assume each function in the array accepts one integer as input and returns one integer as output.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> functions = [x => x + 1, x => x * x, x => 2 * x], x = 4
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<strong>Output:</strong> 65
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<strong>Explanation:</strong>
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Evaluating from right to left ...
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Starting with x = 4.
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2 * (4) = 8
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(8) * (8) = 64
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(64) + 1 = 65
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> functions = [x => 10 * x, x => 10 * x, x => 10 * x], x = 1
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<strong>Output:</strong> 1000
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<strong>Explanation:</strong>
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Evaluating from right to left ...
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10 * (1) = 10
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10 * (10) = 100
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10 * (100) = 1000
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> functions = [], x = 42
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<strong>Output:</strong> 42
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<strong>Explanation:</strong>
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The composition of zero functions is the identity function</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><font face="monospace">-1000 <= x <= 1000</font></code></li>
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<li><code><font face="monospace">0 <= functions.length <= 1000</font></code></li>
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<li><font face="monospace"><code>all functions accept and return a single integer</code></font></li>
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</ul>
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