Find the Longest Substring Having Vowels in Even Counts

class Solution {
public:
    int findTheLongestSubstring(string s) {
        unordered_map<char,int> bit = {{'a',0},{'e',1},{'i',2},{'o',3},{'u',4}};
        vector<int> first(32, -2);
        first[0] = -1;
        int state = 0, ans = 0;
        for (int i = 0; i < (int)s.size(); ++i) {
            auto it = bit.find(s[i]);
            if (it != bit.end()) state ^= (1 << it->second);
            if (first[state] == -2) first[state] = i;
            else ans = max(ans, i - first[state]);
        }
        return ans;
    }
};

func findTheLongestSubstring(s string) int {
    bit := map[byte]int{'a': 0, 'e': 1, 'i': 2, 'o': 3, 'u': 4}
    first := make([]int, 32)
    for i := range first {
        first[i] = -2
    }
    first[0] = -1
    state, ans := 0, 0
    for i := 0; i < len(s); i++ {
        if b, ok := bit[s[i]]; ok {
            state ^= 1 << b
        }
        if first[state] == -2 {
            first[state] = i
        } else if i-first[state] > ans {
            ans = i - first[state]
        }
    }
    return ans
}

class Solution:
    def findTheLongestSubstring(self, s: str) -> int:
        bit = {'a': 0, 'e': 1, 'i': 2, 'o': 3, 'u': 4}
        first = [-2] * 32
        first[0] = -1
        state = 0
        ans = 0
        for i, c in enumerate(s):
            if c in bit:
                state ^= 1 << bit[c]
            if first[state] == -2:
                first[state] = i
            else:
                ans = max(ans, i - first[state])
        return ans

var findTheLongestSubstring = function(s) {
    const bit = { a: 0, e: 1, i: 2, o: 3, u: 4 };
    const first = new Array(32).fill(-2);
    first[0] = -1;
    let state = 0, ans = 0;
    for (let i = 0; i < s.length; i++) {
        const c = s[i];
        if (c in bit) state ^= 1 << bit[c];
        if (first[state] === -2) first[state] = i;
        else ans = Math.max(ans, i - first[state]);
    }
    return ans;
};

class Solution {
    public int findTheLongestSubstring(String s) {
        Map<Character, Integer> bit = new HashMap<>();
        bit.put('a', 0); bit.put('e', 1); bit.put('i', 2); bit.put('o', 3); bit.put('u', 4);
        int[] first = new int[32];
        Arrays.fill(first, -2);
        first[0] = -1;
        int state = 0, ans = 0;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (bit.containsKey(c)) state ^= 1 << bit.get(c);
            if (first[state] == -2) first[state] = i;
            else ans = Math.max(ans, i - first[state]);
        }
        return ans;
    }
}

function findTheLongestSubstring(s: string): number {
    const bit: Record<string, number> = { a: 0, e: 1, i: 2, o: 3, u: 4 };
    const first: number[] = new Array(32).fill(-2);
    first[0] = -1;
    let state = 0, ans = 0;
    for (let i = 0; i < s.length; i++) {
        const c = s[i];
        if (c in bit) state ^= 1 << bit[c];
        if (first[state] === -2) first[state] = i;
        else ans = Math.max(ans, i - first[state]);
    }
    return ans;
}