Benchmark: getCasePermutationsLongerPreAllocatedArray

Script Preparation code:

function getCasePermutationsString(S) {
  let result = [];
  getCasePermutationsStringRecursive(S, 0, '', result);
  return result;
}

function getCasePermutationsStringRecursive(S, idx, substr, result) {
	if (idx === S.length) {
		result.push(substr);
		return;
	}

	const char = S[idx];
	const nextIdx = idx + 1;

	if (char >= '0' && char <= '9') {
		getCasePermutationsStringRecursive(S, nextIdx, substr + char, result);
		return;
	}
	getCasePermutationsStringRecursive(S, nextIdx, substr + char.toLowerCase(), result);
	getCasePermutationsStringRecursive(S, nextIdx, substr + char.toUpperCase(), result);

	return result;
}

function getCasePermutationsArr(S) {
  let result = [];
  let subStrArray = Array(S.length);
  getCasePermutationsArrRecursive(S, 0, subStrArray, result);
  return result;
}

function getCasePermutationsArrRecursive(S, idx, subStrArr, result) {
	if (idx === S.length) {
		result.push(subStrArr.join(''));
		return;
	}

	const char = S[idx];
	const nextIdx = idx + 1;

	if (char >= '0' && char <= '9') {
		subStrArr[idx] = char;
		getCasePermutationsArrRecursive(S, nextIdx, subStrArr, result);
		return;
	}
	subStrArr[idx] = char.toLowerCase();
	getCasePermutationsArrRecursive(S, nextIdx, subStrArr, result);
	
	subStrArr[idx] = char.toUpperCase();
	getCasePermutationsArrRecursive(S, nextIdx, subStrArr, result);
}

Tests:

Array version
const testString = "a1b2c3d4e5f6g7h8i9j0"; getCasePermutationsArr(testString, 0, [], [])
String version
const testString = "a1b2c3d4e5f6g7h8i9j0"; getCasePermutationsString(testString, 0, '', [])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array version
String version

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array version	2886.2 Ops/sec
String version	5947.6 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

Let's break down what is tested on the provided JSON benchmark.

The benchmark measures the performance of two approaches to generate all permutations of a given string: `getCasePermutationsString` and `getCasePermutationsArr`. Both functions are designed to take a string input `S`, and using recursion, generate an array of all possible strings that can be formed by inserting digits (0-9) in the original string.

**Options Compared**

The two options being compared are:

1.  **String version (`getCasePermutationsString`)**: This approach uses recursion to build up all permutations by appending lowercase, uppercase, and numerical characters at each position.
2.  **Array version (`getCasePermutationsArr`)**: This approach also uses recursion but creates an array of substrings instead of a string of permutations.

**Pros and Cons**

*   **String Version ( `getCasePermutationsString` )**:
    *   Pros:
        *   More straightforward to understand due to generating individual permutation strings.
        *   May lead to better cache locality in memory due to fewer data structures involved.
    *   Cons:
        *   Can be more memory-intensive for large inputs, as each permutation is stored on the heap.
*   **Array Version ( `getCasePermutationsArr` )**:
    *   Pros:
        *   More memory-efficient because only a single array needs to be allocated and manipulated for all permutations.
    *   Cons:
        *   May have worse cache locality due to the array operations involved.

**Considerations**

When choosing between these two approaches, consider your specific requirements:

*   If memory is not a concern but speed is crucial, use the `getCasePermutationsString` approach for its potentially better performance.
*   For better memory efficiency and potentially faster execution in scenarios where memory access patterns don't significantly favor cache locality, choose the `getCasePermutationsArr` approach.

**Library Usage**

Neither of these benchmarked functions uses an external library directly. However, they use the following JavaScript built-in features:

*   **Recursion**: A fundamental concept in programming allowing functions to call themselves.
*   **String manipulation**: Utilizes JavaScript's string methods like concatenation and character comparison.

If test cases used special JS features or syntax, there isn't a direct mention of it. However, these examples leverage basic JavaScript capabilities.

**Alternative Approaches**

Some alternative approaches could be considered:

*   **Bit Manipulation Approach**: This method involves converting numbers to binary, then iterating through the binary representation to generate all permutations.
*   **Hybrid Approach**: Combining elements from both the string and array versions by generating a single array with substrings representing characters at each position.

The effectiveness of these alternatives would depend on their implementation details, optimization strategies, and performance characteristics.

This explanation is intended for software engineers familiar or new to JavaScript, providing insight into how to approach similar benchmarking scenarios.

Related benchmarks:

getCasePermutationsLongerPreAllocatedArray (version: 0)

Comparing performance of: Array version vs String version

Created: one year ago by: Guest

Jump to the latest result

Array version

String version

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):