Maximum Compatibility Score Sum LeetCode solution in Java

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class Solution {
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  int max;
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  public int maxCompatibilitySum(int[][] students, int[][] mentors) {
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    boolean[] visited = new boolean[students.length];
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    helper(visited, students, mentors, 0, 0);
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    return max;
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  }
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  public void helper(boolean[] visited, int[][] students, int[][] mentors, int pos, int score) {
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    if (pos >= students.length) {
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      max = Math.max(max, score);
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      return;
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    }
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    for (int i = 0; i < mentors.length; i++)
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      if (!visited[i]) {
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        visited[i] = true;
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        helper(visited, students, mentors, pos + 1, score + score(students[pos], mentors[i]));
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        visited[i] = false;
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      }
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  }
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  public int score(int[] a, int[] b) {
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    int count = 0;
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    for (int i = 0; i < b.length; i++) if (a[i] == b[i]) count += 1;
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    return count;
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  }
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}