Next Greater Element III LeetCode solution in Java

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class Solution {
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  public int nextGreaterElement(int n) {
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    char[] arr = (n + "").toCharArray();
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    int i = arr.length - 1;
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    while (i > 0) {
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      if (arr[i - 1] >= arr[i]) {
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        i--;
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      } else {
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        break;
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      }
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    }
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    if (i == 0) {
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      return -1;
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    }
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    int idx1 = i - 1;
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    int j = arr.length - 1;
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    while (j > idx1) {
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      if (arr[j] > arr[idx1]) {
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        break;
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      }
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      j--;
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    }
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    // Swapping
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    swap(arr, idx1, j);
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    // sorting
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    int left = idx1 + 1;
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    int right = arr.length - 1;
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    while (left < right) {
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      swap(arr, left, right);
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      left++;
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      right--;
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    }
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    String result = new String(arr);
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    long val = Long.parseLong(result);
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    return (val > Integer.MAX_VALUE ? -1 : (int) val);
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  }
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  void swap(char[] arr, int i, int j) {
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    char temp = arr[i];
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    arr[i] = arr[j];
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    arr[j] = temp;
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  }
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}