leetcode-problemset/leetcode-cn/problem (English)/有时间限制的 Promise 对象(English) [promise-time-limit].html

<p>Given an&nbsp;asynchronous function&nbsp;<code>fn</code>&nbsp;and a time <code>t</code>&nbsp;in milliseconds, return&nbsp;a new&nbsp;<strong>time limited</strong>&nbsp;version of the input function. <code>fn</code> takes arguments provided to the&nbsp;<strong>time limited&nbsp;</strong>function.</p>

<p>The <strong>time limited</strong> function should follow these rules:</p>

<ul>
	<li>If the <code>fn</code> completes within the time limit of <code>t</code> milliseconds, the <strong>time limited</strong> function should&nbsp;resolve with the result.</li>
	<li>If the execution of the <code>fn</code> exceeds the time limit, the <strong>time limited</strong> function should reject with the string <code>&quot;Time Limit Exceeded&quot;</code>.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong>
fn = async (n) =&gt; {
&nbsp; await new Promise(res =&gt; setTimeout(res, 100));
&nbsp; return n * n;
}
inputs = [5]
t = 50
<strong>Output:</strong> {&quot;rejected&quot;:&quot;Time Limit Exceeded&quot;,&quot;time&quot;:50}
<strong>Explanation:</strong>
const limited = timeLimit(fn, t)
const start = performance.now()
let result;
try {
&nbsp; &nbsp;const res = await limited(...inputs)
&nbsp; &nbsp;result = {&quot;resolved&quot;: res, &quot;time&quot;: Math.floor(performance.now() - start)};
} catch (err) {
&nbsp;  result = {&quot;rejected&quot;: err, &quot;time&quot;: Math.floor(performance.now() - start)};
}
console.log(result) // Output

The provided function is set to resolve after 100ms. However, the time limit is set to 50ms. It rejects at t=50ms because the time limit was reached.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong>
fn = async (n) =&gt; {
&nbsp; await new Promise(res =&gt; setTimeout(res, 100));
&nbsp; return n * n;
}
inputs = [5]
t = 150
<strong>Output:</strong> {&quot;resolved&quot;:25,&quot;time&quot;:100}
<strong>Explanation:</strong>
The function resolved 5 * 5 = 25 at t=100ms. The time limit is never reached.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong>
fn = async (a, b) =&gt; {
&nbsp; await new Promise(res =&gt; setTimeout(res, 120));
&nbsp; return a + b;
}
inputs = [5,10]
t = 150
<strong>Output:</strong> {&quot;resolved&quot;:15,&quot;time&quot;:120}
<strong>Explanation:</strong>
The function resolved 5 + 10 = 15 at t=120ms. The time limit is never reached.
</pre>

<p><strong class="example">Example 4:</strong></p>

<pre>
<strong>Input:</strong>
fn = async () =&gt; {
&nbsp; throw &quot;Error&quot;;
}
inputs = []
t = 1000
<strong>Output:</strong> {&quot;rejected&quot;:&quot;Error&quot;,&quot;time&quot;:0}
<strong>Explanation:</strong>
The function immediately throws an error.</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= inputs.length &lt;= 10</code></li>
	<li><code>0 &lt;= t &lt;= 1000</code></li>
	<li><code>fn</code> returns a promise</li>
</ul>