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Reduce vs bitwise dividing
(version: 0)
Comparing performance of:
Reduce vs Dividing vs bitwise dividing
Created:
5 years ago
by:
Registered User
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Tests:
Reduce
function s(x) { return x.toString().split('').reduce((total, cur) => total += parseInt(cur), 0); } let x = s(123456789);
Dividing
function s(x) { let sum = 0; while (x > 0) { sum += x % 10; x = Math.floor(x / 10) } return sum; } let x = s(123456789);
bitwise dividing
function s(x) { let sum = 0; while (x > 0) { sum += x % 10; x = ~~(x / 10) } return sum; } let x = s(123456789);
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
Reduce
Dividing
bitwise dividing
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested. **Benchmark Definition** The benchmark defines two different approaches to calculate the sum of digits in a given number: using the `reduce()` method (also known as "Reduce") and using bitwise division. The benchmark uses JavaScript functions, each returning a single value representing the sum of digits. **Options Compared** Two options are compared: 1. **Reduce**: This approach uses the `reduce()` method, which iterates over an array-like object (in this case, the string representation of the number) and applies a callback function to each element, accumulating the result. 2. **Bitwise Dividing**: This approach uses bitwise operations to extract the individual digits from the number and then sums them up. **Pros and Cons** **Reduce:** Pros: * Easy to implement and understand * Built-in in JavaScript, so no extra dependencies required Cons: * May have performance overhead due to the `reduce()` method's iteration mechanism * Can be slower than other approaches for very large numbers **Bitwise Dividing:** Pros: * Typically faster than using `reduce()`, especially for large numbers * Uses basic arithmetic operations, which are often optimized by JavaScript engines Cons: * Requires a good understanding of bitwise operations and how to extract digits from an integer * May require more code and be harder to maintain than the `reduce()` approach **Library Use** None of the benchmark cases use any external libraries. **Special JS Features or Syntax** The benchmark uses the `~~` operator, which is not a standard JavaScript operator. It's an example of a "bitwise trick" used to perform integer division without the decimal part: `x = ~~(x / 10)` This operator performs floor division (`Math.floor(x / 10)`), which discards any fractional part. **Other Alternatives** For calculating the sum of digits, other alternatives could include: * Using `String.prototype.split()` and `Array.prototype.reduce()` * Implementing a custom loop using basic arithmetic operations * Using assembly language or native code (if the benchmark is highly optimized for performance) However, these alternatives would likely require more expertise in JavaScript and are not as straightforward to implement as the `reduce()` approach. **Benchmark Result Interpretation** The latest benchmark result shows that the "bitwise dividing" approach outperforms both "Reduce" approaches, with an average of 284,223.46875 executions per second. This suggests that bitwise division is a more efficient method for calculating the sum of digits in this specific scenario. Keep in mind that these results are highly dependent on the specific JavaScript engine and platform used by the benchmark.
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