Max Difference You Can Get From Changing an Integer LeetCode solution in Java

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class Solution {
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  public int maxDiff(int num) {
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    int[] arr = new int[String.valueOf(num).length()];
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    for (int i = arr.length - 1; i >= 0; i--) {
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      arr[i] = num % 10;
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      num /= 10;
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    }
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    return max(arr.clone()) - min(arr);
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  }
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  private int max(int[] arr) { // find max
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    for (int i = 0, t = -1; i < arr.length; i++) {
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      if (t == -1 && arr[i] != 9) {
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        t = arr[i];
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      }
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      if (t == arr[i]) {
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        arr[i] = 9;
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      }
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    }
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    return parse(arr);
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  }
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  private int min(int[] arr) { // find min
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    int re = arr[0] == 1 ? 0 : 1;
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    int t = arr[0] == 1 ? -1 : arr[0];
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    for (int i = 0; i < arr.length; i++) {
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      if (t == -1 && arr[i] != 0 && arr[i] != arr[0]) {
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        t = arr[i];
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      }
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      if (t == arr[i]) {
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        arr[i] = re;
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      }
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    }
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    return parse(arr);
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  }
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  private int parse(int[] arr) {
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    int ans = 0;
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    for (int i = 0; i < arr.length; i++) {
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      ans = 10 * ans + arr[i];
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    }
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    return ans;
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  }
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}