Java String Exercises: Find longest Palindromic Substring within a string

Java String: Exercise-32 with Solution

Write a Java program to find longest Palindromic Substring within a string.

Pictorial Presentation:

Sample Solution:

Java Code:

import java.util.*;
public class Main {
 static void printSubStr(String str1, int l, int h) {
  System.out.println(str1.substring(l, h + 1));
 }

 static int longPalSubstr(String str1) {
  int n = str1.length();
  boolean table[][] = new boolean[n][n];
  int mLength = 1;
  for (int i = 0; i < n; ++i)
   table[i][i] = true;
  int strt = 0;
  for (int i = 0; i < n - 1; ++i) {
   if (str1.charAt(i) == str1.charAt(i + 1)) {
    table[i][i + 1] = true;
    strt = i;
    mLength = 2;
   }
  }
  for (int k = 3; k <= n; ++k) {
   for (int i = 0; i < n - k + 1; ++i) {
    int j = i + k - 1;
    if (table[i + 1][j - 1] && str1.charAt(i) == str1.charAt(j)) {
     table[i][j] = true;

     if (k > mLength) {
      strt = i;
      mLength = k;
     }
    }
   }
  }
  System.out.print("The longest palindrome substring in the given string is; ");
  printSubStr(str1, strt, strt + mLength - 1);
  return mLength;
 }
 public static void main(String[] args) {
  String str1 = "thequickbrownfoxxofnworbquickthe";
  System.out.println("The given string is: " + str1);
  System.out.println("The length of the palindromic substring is: " + longPalSubstr(str1));
 }
}

Sample Output:

The given string is: thequickbrownfoxxofnworbquickthe
The longest palindrome substring in the giv
en string is; brownfoxxofnworb
The length of the palindromic substring is: 16

Flowchart:

Java Code Editor:

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