Leetcode_1371.java

class Solution {

    public int findTheLongestSubstring(String s) {
        int prefixXOR = 0;
        int[] characterMap = new int[26];
        characterMap['a' - 'a'] = 1;
        characterMap['e' - 'a'] = 2;
        characterMap['i' - 'a'] = 4;
        characterMap['o' - 'a'] = 8;
        characterMap['u' - 'a'] = 16;
        int[] mp = new int[32];
        for (int i = 0; i < 32; i++) mp[i] = -1;
        int longestSubstring = 0;
        for (int i = 0; i < s.length(); i++) {
            prefixXOR ^= characterMap[s.charAt(i) - 'a'];
            if (mp[prefixXOR] == -1 && prefixXOR != 0) mp[prefixXOR] = i;
            longestSubstring = Math.max(longestSubstring, i - mp[prefixXOR]);
        }
        return longestSubstring;
    }
}