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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0501_0600.s0521_longest_uncommon_subsequence_i;

// #Easy #String #2022_07_28_Time_0_ms_(100.00%)_Space_40.2_MB_(87.89%)

/**
 * 521 - Longest Uncommon Subsequence I\.
 *
 * Easy
 *
 * Given two strings `a` and `b`, return _the length of the **longest uncommon subsequence** between_ `a` _and_ `b`. If the longest uncommon subsequence does not exist, return `-1`.
 *
 * An **uncommon subsequence** between two strings is a string that is a **subsequence of one but not the other**.
 *
 * 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:** a = "aba", b = "cdc"
 *
 * **Output:** 3
 *
 * **Explanation:** One longest uncommon subsequence is "aba" because "aba" is a subsequence of "aba" but not "cdc". Note that "cdc" is also a longest uncommon subsequence.
 *
 * **Example 2:**
 *
 * **Input:** a = "aaa", b = "bbb"
 *
 * **Output:** 3
 *
 * **Explanation:** The longest uncommon subsequences are "aaa" and "bbb".
 *
 * **Example 3:**
 *
 * **Input:** a = "aaa", b = "aaa"
 *
 * **Output:** -1
 *
 * **Explanation:** Every subsequence of string a is also a subsequence of string b. Similarly, every subsequence of string b is also a subsequence of string a.
 *
 * **Constraints:**
 *
 * *   `1 <= a.length, b.length <= 100`
 * *   `a` and `b` consist of lower-case English letters.
**/
public class Solution {
    /*
     * The gotcha point of this question is:
     * 1. if a and b are identical, then there will be no common subsequence, return -1
     * 2. else if a and b are of equal length, then any one of them will be a subsequence of the other string
     * 3. else if a and b are of different length, then the longer one is a required subsequence because
     * the longer string cannot be a subsequence of the shorter one
     * Or in other words, when a.length() != b.length(), no subsequence of b will be equal to a,
     * so return Math.max(a.length(), b.length())
     */
    public int findLUSlength(String a, String b) {
        if (a.equals(b)) {
            return -1;
        }
        return Math.max(a.length(), b.length());
    }
}