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Problem 4: Largest palindrome product

curriculum/challenges/english/blocks/project-euler-problems-1-to-100/5900f3701000cf542c50fe83.md

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--description--

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Find the largest palindrome made from the product of two n-digit numbers.

--hints--

largestPalindromeProduct(2) should return a number.

js
assert.isNumber(largestPalindromeProduct(2));

largestPalindromeProduct(2) should return 9009.

js
assert.strictEqual(largestPalindromeProduct(2), 9009);

largestPalindromeProduct(3) should return 906609.

js
assert.strictEqual(largestPalindromeProduct(3), 906609);

--seed--

--seed-contents--

js
function largestPalindromeProduct(n) {

  return true;
}

largestPalindromeProduct(3);

--solutions--

js
const largestPalindromeProduct = (digit)=>{
  let start = 1;
  let end = Number(`1e${digit}`) - 1;
 let palindrome = [];
  for(let i=start;i<=end;i++){
    for(let j=start;j<=end;j++){
      let product = i*j;
      let palindromeRegex = /\b(\d)(\d?)(\d?).?\3\2\1\b/gi;
      palindromeRegex.test(product) && palindrome.push(product);
    }
 }
 return Math.max(...palindrome);
}