Detection and Removal of Cycle in Linked List in c++ Algorithm

 

Algorithm for detection and removal of cycle in linked list using Floyd's cycle-finding algorithm and a hash table:

1. Initialize two pointers, 'slow' and 'fast', to the head of the linked list.
2. Create an unordered_set container to store visited nodes.
3. Use a while loop to iterate through the linked list. In each iteration, move the 'slow' pointer one node at a time and the 'fast' pointer two nodes at a time.
4. Check if the 'slow' pointer is in the unordered_set container. If it is, a cycle has been detected.
5. If a cycle is detected, initialize a new pointer 'last' to the 'slow' pointer.
6. Use another while loop to iterate through the cycle, starting from the 'last' pointer, until the 'last' pointer points to the 'slow' pointer.
7. Set the next pointer of the 'last' pointer to NULL, breaking the cycle.
8. If the 'slow' pointer is not in the unordered_set container, add it to the set of visited nodes.
9. Repeat steps 3-8 until the end of the linked list is reached.
10. If the 'fast' pointer is NULL or the 'fast' pointer's next pointer is NULL, return false, indicating that there is no cycle in the linked list.
11. If the 'slow' pointer and 'fast' pointer are equal, return true, indicating that there is a cycle in the linked list.

It's important to note that, this algorithm has a time complexity of O(n) and a space complexity of O(n) as it uses hash table to keep track of the visited nodes.