Given the head node of a linked list, determine whether the list contains a cycle. Return true if the list contains a cycle; otherwise, return false.
A linked list has a cycle if there exists a node that can be revisited by continuously following the next pointers.
The linked list is represented by a sequence of ListNodes, where each node points to the next node in the sequence, or null if it is the last node.
A ListNode has the following interface:
interface ListNode {val: number;next: ListNode | null;}
head: ListNode: Head of the linked list. Examples display each linked list as an array of values within the listInput: list = [1,2,3], pos = 0Output: trueExplanation: The linked list is constructed from the array [1, 2, 3] with the pos = 0, which means the last node (value 3) connects back to the 0th node (value 1). The structure of the linked list is: 1 -> 2 -> 3 -> (back to 1). This forms a cycle starting from node 1. Hence, the output is true.
Input: list = [1], pos = -1Output: falseExplanation: The linked list has only one node with the value 1. The pos = -1 indicates that the last node does not connect to any other node. The structure of the linked list is: 1 -> null. Since the list terminates with null and does not loop back to any earlier node, it does not contain a cycle. Hence, the output is false.
Input: list = [3,2,0,-4], pos = 1Output: trueExplanation: The linked list is constructed from the array [3, 2, 0, -4] with the pos = 1, which means the last node (value -4) connects back to the 1st node (value 2). The structure of the linked list is: 3 -> 2 -> 0 -> -4 -> (back to 2). This forms a cycle starting at node 2. Hence, the output is true.
ListNode.val <= 1000Given the head node of a linked list, determine whether the list contains a cycle. Return true if the list contains a cycle; otherwise, return false.
A linked list has a cycle if there exists a node that can be revisited by continuously following the next pointers.
The linked list is represented by a sequence of ListNodes, where each node points to the next node in the sequence, or null if it is the last node.
A ListNode has the following interface:
interface ListNode {val: number;next: ListNode | null;}
head: ListNode: Head of the linked list. Examples display each linked list as an array of values within the listInput: list = [1,2,3], pos = 0Output: trueExplanation: The linked list is constructed from the array [1, 2, 3] with the pos = 0, which means the last node (value 3) connects back to the 0th node (value 1). The structure of the linked list is: 1 -> 2 -> 3 -> (back to 1). This forms a cycle starting from node 1. Hence, the output is true.
Input: list = [1], pos = -1Output: falseExplanation: The linked list has only one node with the value 1. The pos = -1 indicates that the last node does not connect to any other node. The structure of the linked list is: 1 -> null. Since the list terminates with null and does not loop back to any earlier node, it does not contain a cycle. Hence, the output is false.
Input: list = [3,2,0,-4], pos = 1Output: trueExplanation: The linked list is constructed from the array [3, 2, 0, -4] with the pos = 1, which means the last node (value -4) connects back to the 1st node (value 2). The structure of the linked list is: 3 -> 2 -> 0 -> -4 -> (back to 2). This forms a cycle starting at node 2. Hence, the output is true.
ListNode.val <= 1000console.log() 语句将显示在此处。