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Longest Palindromic Substring

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a C program to find the longest palindromic substring in a given string. A palindrome is a string that reads the same forward and backward. If there are multiple palindromic substrings of the same maximum length, return any one of them.

Example 1
    
  
  • Input: s = "babad"
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  • Output: "bab"
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  • Explanation: 
     Step 1: Check all possible substrings for palindrome property.

     Step 2: "bab" is a palindrome of length 3.

     Step 3: "aba" is also a palindrome of length 3.

     Step 4: Both are valid answers, so we return "bab".
    •
Example 2
    
  
  • Input: s = "cbbd"
    • 
  
  • Output: "bb"
    • 
  
  • Explanation: 
     Step 1: Check all possible substrings for palindrome property.

     Step 2: "bb" is a palindrome of length 2.

     Step 3: No longer palindrome exists in the string.

     Step 4: Therefore, "bb" is the longest palindromic substring.
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Constraints
    
  
  • 1 ≤ s.length ≤ 1000
    • 
  
  • s consists of only lowercase English letters
    • 
  
  • Time Complexity: O(n^2)
    • 
  
  • Space Complexity: O(1)
    •
StringsHCL TechnologiesAirbnb
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Hint
Solution

Solution Hints

    
  
  • Use the "expand around centers" approach.
    • 
  
  • For each character, consider it as the center of a palindrome.
    • 
  
  • Expand outward while characters match on both sides.
    • 
  
  • Handle both odd-length and even-length palindromes.
    • 
  
  • Keep track of the longest palindrome found so far.
    •

Steps to solve by this approach:

 Step 1: Initialize variables to track the start position and maximum length of palindrome found.
 Step 2: For each character position, treat it as the center of an odd-length palindrome.
 Step 3: Expand outward from the center while characters on both sides match.
 Step 4: Update the longest palindrome if a longer one is found.
 Step 5: Repeat the process for even-length palindromes by considering adjacent characters as centers.
 Step 6: Extract and return the substring corresponding to the longest palindrome found.
 Step 7: Handle memory allocation for the result string properly.

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