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LongestPalindromicSubstring #1486

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ZainabMalik5 Oct 5, 2023

Delete Maths/Divisors.js

ZainabMalik5 Oct 8, 2023

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ZainabMalik5 Oct 9, 2023

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42 changes: 42 additions & 0 deletions Dynamic-Programming/LongestPalindromicSubstring.js

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Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,42 @@
	/*
	LeetCode -> https://leetcode.com/problems/longest-palindromic-substring

	Given a string s, find the longest palindromic substring in s.
	You may assume that the maximum length of s is 1000.

	*/
	function longestPalindrome(s) {
	const n = s.length;
	const dp = new Array(n + 1).fill(0).map(() => new Array(n + 1).fill(0));
	const len = new Array(n + 1).fill(0).map(() => new Array(n + 1).fill(0));
	let str = "";
	let mx = 0;
	//fill for single chracter
	for (let i = 0; i < n; i++) {
	dp[i][i] = 1;
	len[i][i] = 1;
	}

	for (let i = n - 2; i >= 0; i--) {
	for (let j = i + 1; j < n; j++) {
	if (s[i] === s[j] && j - i === 1) {
	len[i][j] = 2;
	dp[i][j] = 1;
	} else if (s[i] === s[j] && dp[i + 1][j - 1]) {
	dp[i][j] = 1;
	len[i][j] = j - i + 1;
	}
	}
	}

	for (let i = 0; i < n; i++) {
	for (let j = 0; j < n; j++) {
	if (len[i][j] > mx && dp[i][j]) {
	mx = len[i][j];
	str = s.substring(i, j + 1);
	}
	}
	}

	return str;
	}