Untitled

package array;

public class ArrayApp {

  public static boolean checkIfCircularArrayHasCycle(int[] arr) {
    if(arr.length <= 1) {
      return false;
    }
    
    for(int i = 0; i < arr.length; i++) {
      
      int slow, fast;
      slow = fast = i;
      boolean ifForward = arr[i] > 0;
      
      while(true) {
        slow = getNextPosition(arr, slow, ifForward);
        if(slow == -1) {
          break;
        }
        
        fast = getNextPosition(arr, fast, ifForward);
        if(fast == -1) {
          break;
        }
        
        fast = getNextPosition(arr, fast, ifForward);
        if(fast == -1) {
          break;
        }
        
        if(slow == fast) {
          return true;
        }  
      }
    }
    
    return false;
  }
  
  private static int getNextPosition(int[] arr, int index, boolean ifForward) {
    boolean direction = arr[index] >= 0;
    
    if(direction != ifForward) {
      return -1;
    }
    
    int nextIndex = (index + arr[index]) % arr.length;
    
    if(nextIndex < 0) {
      nextIndex = nextIndex + arr.length;
    }
    
    if(nextIndex == index) {
      return -1;
    }
    
    return nextIndex;
  }

  
  public static void main(String[] args) {
    int[] arr = {1, 1, 2, 1, 2};

    System.out.println(ArrayApp.checkIfCircularArrayHasCycle(arr));
  }

}