Yes, if the linked list contains a cycle, the fast and slow pointer will always meet at some point. Read more here Q.2: Will the fast and slow pointer always meet at some point if the list contains a cycle?Īns. A loop can be detected efficiently using the fast and slow pointer algorithm, where the fast pointer moves by two nodes and the slow pointer move by one node at a time. Using Iterators to remove elements from a Java Collection. Java - removing an element in list while iterating it with a for index loop. Heres a thought experiment for you to go through. If you think about how the computer has to reconcile it, it makes sense. Note that this means you cant use the enhanced for loop. It is problematic to iterate over a list and remove elements while iterating over it. for (Iterator iter list.listIterator() iter.hasNext() ). Two options: Create a list of values you wish to remove, adding to that list within the loop, then call originalList.removeAll(valuesToRemove) at the end Use the remove() method on the iterator itself.Make sure your variable names are correct. Space Complexity: O(1), as a map is used.įAQs Q.1: How do you detect a loop in a linked list?Īns. Youre using iterator but you iterate this list using iter. Time Complexity: O(N), where N is the number of nodes of the linked list.While ptr.next is not slow and ptr.next is not curr: If no node satisfies the above conditions, then the linked list does not contain any cycle.Ĭ++ Implementation void hashAndRemove(Node * head) Python Code def removeCycle(slow, head):.Else, continue traversing and continue inserting the node into the HashSet.If the current node is already present in the hashmap, it ensures that the linked list contains a loop.Traverse the linked list till the head pointer isnât NULL:.Statement 3 increases a value (i++) each time the code block in the loop has been executed. If the condition is true, the loop will start over again, if it is false, the loop will end. But problem is that when the first plan are been deleted, system wont go to other tariff and exiting the for loop. In my case I have 2 tarifs which I need to remove. Statement 2 defines the condition for the loop to run (i must be less than 5). I should to check every tariff and remove it from Plans if type not equals 'L'. If a node has already occurred before, simply set the current pointer to NULL. Statement 1 sets a variable before the loop starts (int i 0). Note: It is not recommended to use ArrayList.remove () when iterating over elements. To perform this operation, a hashmap can be used. There are 3 ways to remove an element from ArrayList as listed which later on will be revealed as follows: Using remove () method by indexes (default) Using remove () method by values. The most straightforward approach to solve this problem is to check whether a node in the linked list has been visited before. In 4 simple steps you can find your personalised career roadmap in Software development for FREE
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