Package g0401_0500.s0457_circular_array_loop

Class Solution

java.lang.Object
g0401_0500.s0457_circular_array_loop.Solution
public class Solution extends Object
457 - Circular Array Loop\. Medium You are playing a game involving a **circular** array of non-zero integers `nums`. Each `nums[i]` denotes the number of indices forward/backward you must move if you are located at index `i`: * If `nums[i]` is positive, move `nums[i]` steps **forward** , and * If `nums[i]` is negative, move `nums[i]` steps **backward**. Since the array is **circular** , you may assume that moving forward from the last element puts you on the first element, and moving backwards from the first element puts you on the last element. A **cycle** in the array consists of a sequence of indices `seq` of length `k` where: * Following the movement rules above results in the repeating index sequence `seq[0] -> seq[1] -> ... -> seq[k - 1] -> seq[0] -> ...` * Every `nums[seq[j]]` is either **all positive** or **all negative**. * `k > 1` Return `true` _if there is a **cycle** in_ `nums`_, or_ `false` _otherwise_. **Example 1:** **Input:** nums = [2,-1,1,2,2] **Output:** true **Explanation:** There is a cycle from index 0 -> 2 -> 3 -> 0 -> ... The cycle's length is 3. **Example 2:** **Input:** nums = [-1,2] **Output:** false **Explanation:** The sequence from index 1 -> 1 -> 1 -> ... is not a cycle because the sequence's length is 1. By definition the sequence's length must be strictly greater than 1 to be a cycle. **Example 3:** **Input:** nums = [-2,1,-1,-2,-2] **Output:** false **Explanation:** The sequence from index 1 -> 2 -> 1 -> ... is not a cycle because nums[1] is positive, but nums[2] is negative. Every nums[seq[j]] must be either all positive or all negative. **Constraints:** * `1 <= nums.length <= 5000` * `-1000 <= nums[i] <= 1000` * `nums[i] != 0` **Follow up:** Could you solve it in `O(n)` time complexity and `O(1)` extra space complexity?

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • circularArrayLoop

      public boolean circularArrayLoop(int[] arr)