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How to find the longest palindrome substring in a bigger string, in Java?

Wissam answered on May 21, 2022 Popularity 10/10 Helpfulness 2/10

answer How to find the longest palindrome substring in a bigger string, in Java?

related Longest Palindrome String in java

How to find the longest palindrome substring in a bigger string, in Java?

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/*
	This implementation demonstrates how to 
	find the longest palindrome substring 
	in a given bigger string. 

	
	Let n be the length of the bigger string.

	Time complexity: O(n^2) 
	Space complexity: O(1)
*/
public class LongestPalindromeSubstring {

	public static void main(String[] args) {
		String s = "babad";
		System.out.println(longestPalindrome(s)); // bab
	}

	private static String longestPalindrome(String s) {
		if (s.length() == 1) {
			return s;
		}

		int maxLength = Integer.MIN_VALUE;
		String longestPalindrome = "";
		int n = s.length();

		for (int index = 0; index < n; index++) {
			for (int x = 0; index - x >= 0 && index + x < n; x++) {
				if (s.charAt(index - x) == s.charAt(index + x)) {
					int len = 2 * x + 1;
					if (len > maxLength) {
						maxLength = len;
						longestPalindrome = s.substring(index - x, index + x + 1);
					}
				} else {
					break;
				}
			}
		}

		for (int index = 0; index < n - 1; index++) {
			for (int x = 1; index - x + 1 >= 0 && index + x < n; x++) {
				if (s.charAt(index - x + 1) != s.charAt(index + x)) {
					break;
				} else {
					int len = 2 * x;
					if (len > maxLength) {
						maxLength = len;
						longestPalindrome = s.substring(index - x + 1, index + x + 1);
					}
				}
			}
		}

		return longestPalindrome;
	}
}

Popularity 10/10 Helpfulness 2/10 Language java

Source: Grepper

Tags: find java palindrome substring

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Contributed on Jul 19 2022

Wissam

0 Answers Avg Quality 2/10

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Longest Palindrome String in java

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class Solution {
   String getLongestPalindrome(String s) {
       int n = s.length();
       int index  = 0, palindromeLength = 1;
       for (int i = 1; i < n; i++) {
           int left = i - 1, right = i;
           while(left >= 0 && right < n && s.charAt(left) == s.charAt(right)) {
               if(right - left + 1 > palindromeLength) {
                   index = left;
                   palindromeLength = right - left + 1;
               }
               left--;
               right++;
           }
           left = i - 1;
           right = i + 1;
           while(left >= 0 && right < n && s.charAt(left) == s.charAt(right)) {
               if(right - left + 1 > palindromeLength) {
                   index = left;
                   palindromeLength = right - left + 1;
               }
               left--;
               right++;
           }
           
       }
       String ans = "";
       for (int i = index; i < index + palindromeLength; i++) {
           ans += s.charAt(i);
       }
       return ans;
   }
}

Popularity 10/10 Helpfulness 4/10 Language java

Source: workat.tech

Tags: java

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Contributed on May 21 2022

Enchanting Eagle

0 Answers Avg Quality 2/10

Longest Palindrome String in java

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class Solution {
   String getLongestPalindrome(String s) {
       int n = s.length();
       int index  = 0, palindromeLength = 1;
       for (int i = 1; i < n; i++) {
           int left = i - 1, right = i;
           while(left >= 0 && right < n && s.charAt(left) == s.charAt(right)) {
               if(right - left + 1 > palindromeLength) {
                   index = left;
                   palindromeLength = right - left + 1;
               }
               left--;
               right++;
           }
           left = i - 1;
           right = i + 1;
           while(left >= 0 && right < n && s.charAt(left) == s.charAt(right)) {
               if(right - left + 1 > palindromeLength) {
                   index = left;
                   palindromeLength = right - left + 1;
               }
               left--;
               right++;
           }
           
       }
       String ans = "";
       for (int i = index; i < index + palindromeLength; i++) {
           ans += s.charAt(i);
       }
       return ans;
   }
}

Popularity 9/10 Helpfulness 2/10 Language java

Source: workat.tech

Tags: java

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Contributed on May 21 2022

Enchanting Eagle

0 Answers Avg Quality 2/10

How to find the longest palindrome substring in a bigger string, in Java?

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How to find the longest palindrome substring in a bigger string, in Java?

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Longest Palindrome String in java

Longest Palindrome String in java

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