Maximum Number of Achievable Transfer Requests LeetCode solution in Java

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class Solution {
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  int max = 0;
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  public int maximumRequests(int n, int[][] requests) {
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    helper(requests, 0, new int[n], 0);
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    return max;
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  }
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  private void helper(int[][] requests, int index, int[] count, int num) {
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    // Traverse all n buildings to see if they are all 0. (means balanced)
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    if (index == requests.length) {
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      for (int i : count) {
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        if (0 != i) {
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          return;
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        }
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      }
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      max = Math.max(max, num);
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      return;
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    }
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    // Choose this request
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    count[requests[index][0]]++;
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    count[requests[index][1]]--;
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    helper(requests, index + 1, count, num + 1);
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    count[requests[index][0]]--;
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    count[requests[index][1]]++;
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    // Not Choose the request
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    helper(requests, index + 1, count, num);
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  }
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}