Given is an array Arr of integers. The task is to determine if the array has any subsequence of at least length 3 that is a palindrome.
Input: Arr = [1, 2, 1] Output: YES Explanation: Here 1 2 1 is a palindrome. Input: Arr = [1, 1, 2, 2, 3, 3, 4, 4, 5, 5] Output: NO Explanation: Here no subsequence of length at least 3 exists which is a palindrome.
- The idea is to check only for length 3 because if a palindromic subsequence of length greater than 3 exists then there is always a palindromic subsequence of length 3.
- To find the palindromic subsequence of length 3 we just need to find a pair of equal non-adjacent number.
Below is the implementation of the above approach:
- Length of longest Palindromic Subsequence of even length with no two adjacent characters same
- Check if at least half array is reducible to zero by performing some operations
- Smallest Palindromic Subsequence of Even Length in Range [L, R]
- Count pairs (p, q) such that p occurs in array at least q times and q occurs at least p times
- Longest Palindromic Substring using Palindromic Tree | Set 3
- Make palindromic string non-palindromic by rearranging its letters
- Minimum cuts required to convert a palindromic string to a different palindromic string
- Maximum value K such that array has at-least K elements that are >= K
- Maximum length subsequence such that adjacent elements in the subsequence have a common factor
- Length of longest subarray of length at least 2 with maximum GCD
- Construct a string of length L such that each substring of length X has exactly Y distinct letters
- Check if every pair of 1 in the array is at least K length apart from each other
- Check if the given array contains all the divisors of some integer
- Check if all the palindromic sub-strings are of odd length
- Check if a string contains a palindromic sub-string of even length
- Check if a string can be split into even length palindromic substrings
- Longest Palindromic Subsequence | DP-12
- Find the lexicographically largest palindromic Subsequence of a String
- Longest Palindromic Subsequence of two distinct characters
- Count All Palindromic Subsequence in a given String
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