65 lines
1.3 KiB
Markdown
65 lines
1.3 KiB
Markdown
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---
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id: 5900f3701000cf542c50fe83
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title: 'Problem 4: Largest palindrome product'
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challengeType: 5
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forumTopicId: 302065
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dashedName: problem-4-largest-palindrome-product
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---
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# --description--
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A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
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Find the largest palindrome made from the product of two `n`-digit numbers.
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# --hints--
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`largestPalindromeProduct(2)` should return a number.
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```js
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assert(typeof largestPalindromeProduct(2) === 'number');
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```
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`largestPalindromeProduct(2)` should return 9009.
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```js
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assert.strictEqual(largestPalindromeProduct(2), 9009);
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```
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`largestPalindromeProduct(3)` should return 906609.
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```js
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assert.strictEqual(largestPalindromeProduct(3), 906609);
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```
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# --seed--
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## --seed-contents--
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```js
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function largestPalindromeProduct(n) {
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return true;
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}
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largestPalindromeProduct(3);
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```
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# --solutions--
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```js
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const largestPalindromeProduct = (digit)=>{
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let start = 1;
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let end = Number(`1e${digit}`) - 1;
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let palindrome = [];
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for(let i=start;i<=end;i++){
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for(let j=start;j<=end;j++){
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let product = i*j;
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let palindromeRegex = /\b(\d)(\d?)(\d?).?\3\2\1\b/gi;
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palindromeRegex.test(product) && palindrome.push(product);
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}
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}
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return Math.max(...palindrome);
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}
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```
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