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Merge pull request #171 from atk/palindrome-products
new exercise: palindrome-products
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‎config.json

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"prerequisites": [],
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"difficulty": 6
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},
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{
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"slug": "palindrome-products",
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"name": "Palindrome Products",
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"uuid": "96a3edc8-2421-4fb0-b3d1-fb65f48f8230",
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"practices": [],
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"prerequisites": [],
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"difficulty": 7
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},
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{
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"slug": "pig-latin",
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"name": "Pig Latin",

‎exercises/practice/palindrome-products/.docs/instructions.append.md

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## Return values
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The functions are supposed to return the product and the offset and length of the factors array. The factors are just written as pairs of i32 into memory:
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```
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Return value:
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[u32 $product] [u32 $factorsOffset] [u32 $factorsLength]
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Memory at $factorsOffset
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[u32 firstFactor] [u32 firstCofactor] [u32 secondFactor] [u32 secondCofactor] ...
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```
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For the largest one-digit palindrome product, it would look like this:
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```
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Return value
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0009 0000 0004
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Memory at offset 0
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0001 0009 0003 0003
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```

‎exercises/practice/palindrome-products/.docs/instructions.md

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# Instructions
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Detect palindrome products in a given range.
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A palindromic number is a number that remains the same when its digits are reversed.
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For example, `121` is a palindromic number but `112` is not.
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Given a range of numbers, find the largest and smallest palindromes which
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are products of two numbers within that range.
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Your solution should return the largest and smallest palindromes, along with the factors of each within the range.
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If the largest or smallest palindrome has more than one pair of factors within the range, then return all the pairs.
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## Example 1
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Given the range `[1, 9]` (both inclusive)...
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And given the list of all possible products within this range:
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`[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 15, 21, 24, 27, 20, 28, 32, 36, 25, 30, 35, 40, 45, 42, 48, 54, 49, 56, 63, 64, 72, 81]`
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The palindrome products are all single digit numbers (in this case):
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`[1, 2, 3, 4, 5, 6, 7, 8, 9]`
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The smallest palindrome product is `1`.
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Its factors are `(1, 1)`.
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The largest palindrome product is `9`.
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Its factors are `(1, 9)` and `(3, 3)`.
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## Example 2
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Given the range `[10, 99]` (both inclusive)...
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The smallest palindrome product is `121`.
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Its factors are `(11, 11)`.
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The largest palindrome product is `9009`.
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Its factors are `(91, 99)`.

‎exercises/practice/palindrome-products/.eslintrc

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{
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"root": true,
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"extends": "@exercism/eslint-config-javascript",
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"env": {
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"jest": true
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},
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"overrides": [
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{
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"files": [
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"*.spec.js"
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],
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"excludedFiles": [
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"custom.spec.js"
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],
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"extends": "@exercism/eslint-config-javascript/maintainers"
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}
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]
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}

‎exercises/practice/palindrome-products/.meta/config.json

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{
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"authors": [
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"atk"
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],
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"files": {
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"solution": [
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"palindrome-products.wat"
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],
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"test": [
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"palindrome-products.spec.js"
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],
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"example": [
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".meta/proof.ci.wat"
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],
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"invalidator": [
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"package.json"
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]
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},
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"blurb": "Detect palindrome products in a given range.",
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"source": "Problem 4 at Project Euler",
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"source_url": "https://projecteuler.net/problem=4",
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"custom": {
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"version.tests.compatibility": "jest-27",
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"flag.tests.task-per-describe": false,
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"flag.tests.may-run-long": false,
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"flag.tests.includes-optional": false
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}
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}

‎exercises/practice/palindrome-products/.meta/proof.ci.wat

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(module
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(import "console" "log_i32_s" (func $log_i32_s (param i32)))
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(memory (export "mem") 1)
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(global $minMaxError i32 (i32.const -1))
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;;
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;; Find the first palindrome product based on factors inclusively between minFactor and maxFactor, iterating by step
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;;
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;; @param {i32} $minFactor - smallest factor of the product
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;; @param {i32} $maxFactor - largest factor of the product
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;; @param {i32} $step - step
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;;
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;; @returns {(i32,i32,i32)} - product (0 = not found, -1 = error), offset and length of an array of pairwise factors
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;;
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(func $find (param $minFactor i32) (param $maxFactor i32) (param $step i32) (result i32 i32 i32)
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(local $prod i32)
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(local $last i32)
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(local $factor i32)
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(local $cofactor i32)
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(local $num i32)
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(local $rev i32)
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(local $factorsCount i32)
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(if (i32.gt_u (local.get $minFactor) (local.get $maxFactor)) (then
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(return (global.get $minMaxError) (i32.const 0) (i32.const 0))))
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(if (i32.eq (local.get $step) (i32.const 1)) (then
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(local.set $prod (i32.sub (i32.mul (local.get $minFactor) (local.get $minFactor)) (i32.const 1)))
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(local.set $last (i32.mul (local.get $maxFactor) (local.get $maxFactor))))
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(else
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(local.set $prod (i32.sub (i32.mul (local.get $maxFactor) (local.get $maxFactor)) (i32.const -1)))
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(local.set $last (i32.mul (local.get $minFactor) (local.get $minFactor)))))
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(loop $products
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(local.set $prod (i32.add (local.get $prod) (local.get $step)))
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(local.set $num (local.get $prod))
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(local.set $rev (i32.const 0))
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(loop $reverse
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(local.set $rev (i32.add (i32.mul (local.get $rev) (i32.const 10))
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(i32.rem_s (local.get $num) (i32.const 10))))
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(local.set $num (i32.div_u (local.get $num) (i32.const 10)))
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(br_if $reverse (local.get $num)))
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(if (i32.eq (local.get $rev) (local.get $prod)) (then
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(local.set $factor (local.get $minFactor))
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(loop $factorize
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(if (i32.eqz (i32.rem_u (local.get $prod) (local.get $factor))) (then
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(local.set $cofactor (i32.div_u (local.get $prod) (local.get $factor)))
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(if (i32.lt_u (local.get $cofactor) (local.get $factor))
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(then (local.set $factor (local.get $maxFactor)))
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(else (if (i32.and (i32.ge_u (local.get $cofactor) (local.get $minFactor))
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(i32.le_u (local.get $cofactor) (local.get $maxFactor))) (then
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(i32.store (i32.shl (local.get $factorsCount) (i32.const 2)) (local.get $factor))
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(i32.store (i32.shl (i32.add (local.get $factorsCount) (i32.const 1)) (i32.const 2))
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(local.get $cofactor))
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(local.set $factorsCount (i32.add (local.get $factorsCount) (i32.const 2)))))))))
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(local.set $factor (i32.add (local.get $factor) (i32.const 1)))
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(br_if $factorize (i32.le_u (local.get $factor) (local.get $maxFactor))))
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(if (local.get $factorsCount) (then
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(return (local.get $prod) (i32.const 0) (local.get $factorsCount))))
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))
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(br_if $products (i32.ne (local.get $prod) (local.get $last))))
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(i32.const 0) (i32.const 0) (i32.const 0)
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)
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;;
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;; Find the smallest palindrome product based on factors inclusively between minFactor and maxFactor
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;;
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;; @param {i32} $minFactor - smallest factor of the product
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;; @param {i32} $maxFactor - largest factor of the product
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;;
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;; @returns {(i32,i32,i32)} - product (0 = not found, -1 = error), offset and length of an array of pairwise factors
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;;
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(func (export "smallest") (param $minFactor i32) (param $maxFactor i32) (result i32 i32 i32)
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(call $find (local.get $minFactor) (local.get $maxFactor) (i32.const 1))
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)
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;;
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;; Find the largest palindrome product based on factors inclusively between minFactor and maxFactor
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;;
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;; @param {i32} $minFactor - smallest factor of the product
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;; @param {i32} $maxFactor - largest factor of the product
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;;
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;; @returns {(i32,i32,i32)} - product (0 = not found, -1 = error), offset and length of an array of pairwise factors
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;;
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(func (export "largest") (param $minFactor i32) (param $maxFactor i32) (result i32 i32 i32)
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(call $find (local.get $minFactor) (local.get $maxFactor) (i32.const -1))
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)
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)

‎exercises/practice/palindrome-products/.meta/tests.toml

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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[5cff78fe-cf02-459d-85c2-ce584679f887]
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description = "find the smallest palindrome from single digit factors"
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[0853f82c-5fc4-44ae-be38-fadb2cced92d]
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description = "find the largest palindrome from single digit factors"
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[66c3b496-bdec-4103-9129-3fcb5a9063e1]
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description = "find the smallest palindrome from double digit factors"
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[a10682ae-530a-4e56-b89d-69664feafe53]
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description = "find the largest palindrome from double digit factors"
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[cecb5a35-46d1-4666-9719-fa2c3af7499d]
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description = "find the smallest palindrome from triple digit factors"
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[edab43e1-c35f-4ea3-8c55-2f31dddd92e5]
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description = "find the largest palindrome from triple digit factors"
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[4f802b5a-9d74-4026-a70f-b53ff9234e4e]
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description = "find the smallest palindrome from four digit factors"
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[787525e0-a5f9-40f3-8cb2-23b52cf5d0be]
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description = "find the largest palindrome from four digit factors"
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[58fb1d63-fddb-4409-ab84-a7a8e58d9ea0]
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description = "empty result for smallest if no palindrome in the range"
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[9de9e9da-f1d9-49a5-8bfc-3d322efbdd02]
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description = "empty result for largest if no palindrome in the range"
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[12e73aac-d7ee-4877-b8aa-2aa3dcdb9f8a]
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description = "error result for smallest if min is more than max"
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[eeeb5bff-3f47-4b1e-892f-05829277bd74]
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description = "error result for largest if min is more than max"
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[16481711-26c4-42e0-9180-e2e4e8b29c23]
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description = "smallest product does not use the smallest factor"

‎exercises/practice/palindrome-products/.npmrc

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audit=false

‎exercises/practice/palindrome-products/LICENSE

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MIT License
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Copyright (c) 2021 Exercism
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.

‎exercises/practice/palindrome-products/babel.config.js

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export default {
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presets: ["@exercism/babel-preset-javascript"],
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plugins: [],
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};

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