mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-01-10 18:48:13 +08:00
75 lines
3.7 KiB
HTML
75 lines
3.7 KiB
HTML
<p>Given a function <code>fn</code>, return a <strong>memoized</strong> version of that function.</p>
|
|
|
|
<p>A <strong>memoized </strong>function is a function that will never be called twice with the same inputs. Instead it will return a cached value.</p>
|
|
|
|
<p>You can assume there are <strong>3 </strong>possible input functions: <code>sum</code><strong>, </strong><code>fib</code><strong>, </strong>and <code>factorial</code><strong>.</strong></p>
|
|
|
|
<ul>
|
|
<li><code>sum</code><strong> </strong>accepts two integers <code>a</code> and <code>b</code> and returns <code>a + b</code>.</li>
|
|
<li><code>fib</code><strong> </strong>accepts a single integer <code>n</code> and returns <code>1</code> if <font face="monospace"><code>n <= 1</code> </font>or<font face="monospace"> <code>fib(n - 1) + fib(n - 2)</code> </font>otherwise.</li>
|
|
<li><code>factorial</code> accepts a single integer <code>n</code> and returns <code>1</code> if <code>n <= 1</code> or <code>factorial(n - 1) * n</code> otherwise.</li>
|
|
</ul>
|
|
|
|
<p> </p>
|
|
<p><strong class="example">Example 1:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong>
|
|
fnName = "sum"
|
|
actions = ["call","call","getCallCount","call","getCallCount"]
|
|
values = [[2,2],[2,2],[],[1,2],[]]
|
|
<strong>Output:</strong> [4,4,1,3,2]
|
|
<strong>Explanation:</strong>
|
|
const sum = (a, b) => a + b;
|
|
const memoizedSum = memoize(sum);
|
|
memoizedSum(2, 2); // "call" - returns 4. sum() was called as (2, 2) was not seen before.
|
|
memoizedSum(2, 2); // "call" - returns 4. However sum() was not called because the same inputs were seen before.
|
|
// "getCallCount" - total call count: 1
|
|
memoizedSum(1, 2); // "call" - returns 3. sum() was called as (1, 2) was not seen before.
|
|
// "getCallCount" - total call count: 2
|
|
</pre>
|
|
|
|
<p><strong class="example">Example 2:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:
|
|
</strong>fnName = "factorial"
|
|
actions = ["call","call","call","getCallCount","call","getCallCount"]
|
|
values = [[2],[3],[2],[],[3],[]]
|
|
<strong>Output:</strong> [2,6,2,2,6,2]
|
|
<strong>Explanation:</strong>
|
|
const factorial = (n) => (n <= 1) ? 1 : (n * factorial(n - 1));
|
|
const memoFactorial = memoize(factorial);
|
|
memoFactorial(2); // "call" - returns 2.
|
|
memoFactorial(3); // "call" - returns 6.
|
|
memoFactorial(2); // "call" - returns 2. However factorial was not called because 2 was seen before.
|
|
// "getCallCount" - total call count: 2
|
|
memoFactorial(3); // "call" - returns 6. However factorial was not called because 3 was seen before.
|
|
// "getCallCount" - total call count: 2
|
|
</pre>
|
|
|
|
<p><strong class="example">Example 3:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:
|
|
</strong>fnName = "fib"
|
|
actions = ["call","getCallCount"]
|
|
values = [[5],[]]
|
|
<strong>Output:</strong> [8,1]
|
|
<strong>Explanation:
|
|
</strong>fib(5) = 8 // "call"
|
|
// "getCallCount" - total call count: 1
|
|
</pre>
|
|
|
|
<p> </p>
|
|
<p><strong>Constraints:</strong></p>
|
|
|
|
<ul>
|
|
<li><code>0 <= a, b <= 10<sup>5</sup></code></li>
|
|
<li><code>1 <= n <= 10</code></li>
|
|
<li><code>0 <= actions.length <= 10<sup>5</sup></code></li>
|
|
<li><code>actions.length === values.length</code></li>
|
|
<li><code>actions[i]</code> is one of "call" and "getCallCount"</li>
|
|
<li><code>fnName</code> is one of "sum", "factorial" and "fib"</li>
|
|
</ul>
|