Circular Array Loop LeetCode solution in Java

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class Solution {
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  public boolean circularArrayLoop(int[] nums) {
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    for (int i = 0; i < nums.length; i++) {
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      boolean isForward = nums[i] > 0;
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      int slow = i;
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      int fast = i;
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      do {
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        slow = findNextIndex(nums, isForward, slow);
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        fast = findNextIndex(nums, isForward, fast);
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        if (fast != -1) {
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          fast = findNextIndex(nums, isForward, fast);
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        }
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      } while (slow != -1 && fast != -1 && slow != fast);
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      if (slow != -1 && slow == fast) {
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        return true;
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      }
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    }
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    return false;
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  }
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  private int findNextIndex(int[] arr, boolean isForward, int currentIndex) {
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    boolean direction = arr[currentIndex] >= 0;
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    if (isForward != direction) {
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      return -1;
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    }
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    int nextIndex = (currentIndex + arr[currentIndex]) % arr.length;
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    if (nextIndex < 0) {
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      nextIndex += arr.length;
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    }
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    if (nextIndex == currentIndex) {
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      nextIndex = -1;
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    }
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    return nextIndex;
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  }
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}