Find the Duplicate Number LeetCode solution in Java

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class Solution {
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  public int findDuplicate(int[] nums) {
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    int i = 0;
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    while (i < nums.length) {
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      if (nums[i] != i + 1) {
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        int correct = nums[i] - 1;
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        if (nums[i] != nums[correct]) {
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          swap(nums, i, correct);
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        } else {
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          return nums[i];
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        }
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      } else {
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        i++;
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      }
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    }
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    return -1;
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  }
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  static void swap(int[] arr, int first, int second) {
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    int temp = arr[first];
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    arr[first] = arr[second];
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    arr[second] = temp;
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  }
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}