AlgoDaily - Length of Longest Palindromic Subsequence

Length of Longest Palindromic Subsequence (Hard)

Good evening! Here's our prompt for today.

Question/Prompt

A palindrome is a word, phrase, or sequence that reads the same backward or forwards. A palindromic subsequence is a palindrome derived from a sequence by deleting some or no elements from it. This subsequence is formed without changing the order of the elements in the original sequence.

Given a string s, can you find the length of the longest palindromic subsequence of s?

For example, if s = "bbbab", then the longest palindromic subsequence is bbbb. The length of this subsequence is 4, which is the required answer.

Constraints

1 <= s.length <= 1000
s consists only of lowercase English letters.

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​
 
var assert = require('assert');
​
function longestPalindromeSubseq(s) {
    // add your code here
    return;
}
​
try {
    assert.deepEqual(longestPalindromeSubseq('bbbab'), 4);
    console.log('PASSED: ' + "`longestPalindromeSubseq('bbbab')` should return `4`");
} catch (err) {
    console.log(err);
}
​
try {
    assert.deepEqual(longestPalindromeSubseq('cbbd'), 2);
    console.log('PASSED: ' + "`longestPalindromeSubseq('cbbd')` should return `2`");
} catch (err) {
    console.log(err);
}
​
try {
    assert.deepEqual(longestPalindromeSubseq('abbcdabbc'), 5);
    console.log('PASSED: ' + "`longestPalindromeSubseq('abbcdabbc')` should return `5`");
} catch (err) {
    console.log(err);
}

OUTPUT

Results will appear here.