removing a loop in a linked list stack overflow

#Removing a loop in a linked list stack overflow code

This node would be the starting node of the loop in the linked list. The trick is to find the first node in the linked list that is reachable from the loop node. If a cycle is found, remove it using that loop node. If both pointers meet at some point, a cycle is found in the list.įirst, the idea is to check if a cycle is present in a linked list using Floyd’s cycle detection algorithm and get a pointer to the loop node where fast and slow pointers meet.

Using Floyd’s Cycle Detection AlgorithmĪs seen in the previous post, Floyd’s cycle detection algorithm maintains two pointers where the first pointer moves at twice the speed of the second pointer. The time complexity of the above solution is O(n) and requires O(n) extra space, where n is the total number of nodes in the linked list.

#Removing a loop in a linked list stack overflow code

The code uses two pointers: curr and prev, where curr is the main pointer running down the list, and prev trails it. To break the cycle, set the next pointer of the previous node to null.įollowing is the implementation of the above idea in C++, Java, and Python. If the node is already present in the HashSet, that means it is seen before and points to the first node in the cycle. The idea is to traverse the given linked list and insert each encountered node into a hash set.

Using HashingĪ simple solution is to use hashing. This post provides an overview of some available alternatives to accomplish this – using hashing and Floyd’s cycle detection algorithm.ĭetect cycle in a linked list (Floyd’s Cycle Detection Algorithm) 1.

The solution should remove the cycle from the list. Given a linked list of integers, which may contain a cycle, remove the cycle if present.įor example, the following linked list has a cycle in it: