Leetcode•Apr 15, 2026

Longest Uncommon Subsequence II

Hazrat Ali

Leetcode

Given an array of strings strs, return the length of the longest uncommon subsequence between them. If the longest uncommon subsequence does not exist, return -1.

An uncommon subsequence between an array of strings is a string that is a subsequence of one string but not the others.

A subsequence of a string s is a string that can be obtained after deleting any number of characters from s.

  • For example, "abc" is a subsequence of "aebdc" because you can delete the underlined characters in "aebdc" to get "abc". Other subsequences of "aebdc" include "aebdc", "aeb", and "" (empty string).

 

Example 1:

Input: strs = ["aba","cdc","eae"]
Output: 3

Example 2:

Input: strs = ["aaa","aaa","aa"]
Output: -1

Solution
var findLUSlength = function(strs) {

    strs.sort((a, b) => b.length - a.length);

    for (let i = 0; i < strs.length; i++) {
        let isUncommon = true;

        for (let j = 0; j < strs.length; j++) {
            if (i === j) continue;

            if (isSubsequence(strs[i], strs[j])) {
                isUncommon = false;
                break;
            }
        }

        if (isUncommon) {
            return strs[i].length;
        }
    }

    return -1;
};


function isSubsequence(a, b) {
    let i = 0, j = 0;

    while (i < a.length && j < b.length) {
        if (a[i] === b[j]) i++;
        j++;
    }

    return i === a.length;
}




Comments