课程: Java Algorithms

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Solution: Detect a cylic linkedlist

Solution: Detect a cylic linkedlist - Java教程

课程: Java Algorithms

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Solution: Detect a cylic linkedlist

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- [Instructor] Let's create an algorithm that detects if a linked list has a cycle. Here we're given the ListNode class where each instance contains a piece of data and a next reference. In order to determine if a list has a cycle, we'll need to use these next pointers. We'll need to check that a given next pointer is not pointing to a node we've already seen in the list. This is a question of membership, which makes the hash set a great tool for this algorithm. In our function, we'll iterate through the linked list, and every time we see a new node, we'll check if it's in the hash set. If it's not, we'll add it to the set. If it is in the hash set, this means we've seen the node before and the list has a cycle. If we can get through the whole list without seeing the same node twice, we can be confident that the list does not have a cycle. Let's implement this idea in code. To start, we'll create a new hash set…

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