Find the Longest Substring Containing Vowels in Even Counts LeetCode solution in Java

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class Solution {
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  // taken help as for my code TLE T.C = (n^2);
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  /*    static boolean check(String s){
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      int n = s.length();
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      int arr[] = new int[26];
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      for(int i=0; i<n; i++){
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          int a = s.charAt(i)-97;
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          arr[a]++;
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      }
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      if(arr[0]%2!=0 || arr[4]%2!=0 || arr[8]%2!=0 || arr[14]%2!=0 ||arr[20]%2!=0) return false;
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      else return true;
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  }
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  static int helper(String str){
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      int ans = 0;
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      int n = str.length();
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      StringBuilder s = new StringBuilder(str);
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      for(int k=1; k<=n; k++){
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          for(int i=0; i<=n-k; i++){
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              String x = s.substring(i,i+k);
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              if(check(x)){
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                  ans = Math.max(ans,k);
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                  break;
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              }
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          }
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      }
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      return ans;
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  }
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  */
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  public int findTheLongestSubstring(String s) {
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    int[] map = new int[32];
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    Arrays.fill(map, -2);
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    map[0] = -1;
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    int n = s.length(), mask = 0, len = 0;
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    for (int i = 0; i < n; i++) {
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      char ch = s.charAt(i);
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      if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u')
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        mask ^= 1 << (4 - (ch == 'a' ? 0 : ch == 'e' ? 1 : ch == 'i' ? 2 : ch == 'o' ? 3 : 4));
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      if (map[mask] == -2) map[mask] = i;
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      else len = Math.max(len, i - map[mask]);
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    }
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    return len;
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  }
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}