52 lines
1.4 KiB
Markdown
52 lines
1.4 KiB
Markdown
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---
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title: Largest palindrome product
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---
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## Problem 4: Largest palindrome product
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### Method:
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- A palindromic number is the one that when reversed reads the same.
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- The largest number obtained from product of two 3 digit number is `999 * 999`, so we can make a loop that starts by producting the largest number and check if that number is palindromic or not.
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### Solution:
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```js
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function largestPalindromeProduct(n) {
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//To get the maximum n digit number, + operator type castes String to Number type
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let max = +[...Array(n)].reduce((a, c) => a+=9, "");
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//Next we get minimum n digit number from the max
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let min = (max+1)/10;
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//To store the result
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let res = [];
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//Starting the loop from max to min
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for (let i = max; i >= min; i--){
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//Another loop
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for (let j = max; j >= min; j--){
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//Getting the product
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let num = i*j;
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//Reversing the number
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let numReverse = [...String(num)].reverse().join('');
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//Checking for palindromic number
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if (num == numReverse) {
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//Pushing the number into array and breaking the loop for efficiency
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res.push(num);
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break;
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}
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}
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}
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// Returning the maximum of the result array
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return Math.max(...res);
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}
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```
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- [Run Code](https://repl.it/@ezioda004/Problem-4-Largest-palindrome-product)
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### References:
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- [Wikipedia](https://en.wikipedia.org/wiki/Palindromic_number)
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