LinkedList

Data structures · pkg3datastructures/datastructures1SinglyLinkedList.java · pkg3datastructures · datastructures1SinglyLinkedList.java

Data structures · pkg3datastructures/datastructures2DoublyLinkedList.java · pkg3datastructures · datastructures2DoublyLinkedList.java

Helpers · pkg5leetcode/common/ListNode.java · pkg5leetcode · ListNode.java

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC141LinkedListCycle.java · pkg5leetcode · blind75_LC141LinkedListCycle.java

Floyd slow/fast pointers detect cycle. Time O(n), Space O(1)

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC143ReorderList.java · pkg5leetcode · blind75_LC143ReorderList.java

Find middle, reverse second half, merge alternating. Time O(n), Space O(1)

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC19RemoveNthNodeFromEnd.java · pkg5leetcode · blind75_LC19RemoveNthNodeFromEnd.java

Two pointers n+1 apart; delete node after slow. Time O(n), Space O(1)

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC206ReverseLinkedList.java · pkg5leetcode · blind75_LC206ReverseLinkedList.java

Iterative three-pointer reversal. Time O(n), Space O(1)

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC21MergeTwoSortedLists.java · pkg5leetcode · blind75_LC21MergeTwoSortedLists.java

Dummy head merge two pointers. Time O(n+m), Space O(1)

Blind 75 · Linked List · pkg5leetcode/blind75/blind75_LC23MergeKSortedLists.java · pkg5leetcode · blind75_LC23MergeKSortedLists.java

Min-heap of list heads by value. Time O(N log k), Space O(k)

Interview 150 · pkg5leetcode/interview150/interview150_LC146LRUCache.java · pkg5leetcode · interview150_LC146LRUCache.java

HashMap + doubly linked list for O(1) get/put eviction. Time O(1) per op, Space O(capacity)

Interview 150 · pkg5leetcode/interview150/interview150_LC234PalindromeLinkedList.java · pkg5leetcode · interview150_LC234PalindromeLinkedList.java

Find middle, reverse second half, compare halves. Time O(n), Space O(1)

Interview 150 · pkg5leetcode/interview150/interview150_LC876MiddleOfTheLinkedList.java · pkg5leetcode · interview150_LC876MiddleOfTheLinkedList.java

Slow/fast pointers; slow at middle when fast reaches end. Time O(n), Space O(1)

Starter · Linked list · pkg5leetcode/leetcode9ReverseLinkedList.java · pkg5leetcode · leetcode9ReverseLinkedList.java

Reverse a singly linked list. Shown iteratively and recursively. Time O(n); iterative Space O(1), recursive Space O(n) (call stack).

LeetCode 75 · Linked List · pkg5leetcode/official75/official75_LC206ReverseLinkedList.java · pkg5leetcode · official75_LC206ReverseLinkedList.java

Iterative three-pointer reversal. Time O(n), Space O(1)

LeetCode 75 · Linked List · pkg5leetcode/official75/official75_LC2095DeleteTheMiddleNodeOfALinkedList.java · pkg5leetcode · official75_LC2095DeleteTheMiddleNodeOfALinkedList.java

Slow/fast pointers; delete node after slow. Time O(n), Space O(1)

LeetCode 75 · Linked List · pkg5leetcode/official75/official75_LC2130MaximumTwinSumOfALinkedList.java · pkg5leetcode · official75_LC2130MaximumTwinSumOfALinkedList.java

Find mid, reverse second half, max pair sum. Time O(n), Space O(1)

LeetCode 75 · Linked List · pkg5leetcode/official75/official75_LC328OddEvenLinkedList.java · pkg5leetcode · official75_LC328OddEvenLinkedList.java

Two chains for odd/even indices then connect. Time O(n), Space O(1)

Top 100 · pkg5leetcode/top100/top100_LC114FlattenBinaryTreeToLinkedList.java · pkg5leetcode · top100_LC114FlattenBinaryTreeToLinkedList.java

Morris traversal flatten right then left into preorder tail. Time O(n), Space O(1)

Collections Framework — Interview Questions (120+)

ArrayList = array (fast random access); LinkedList = nodes (fast head/tail ops).

Collections Framework — Interview Questions (120+)

By access pattern: order, uniqueness, sorting, concurrency.

Performance & Tuning — Interview Questions (60+)

Profile, fix the biggest bottleneck, verify, repeat.

Deterministic link

co-mentioned in interview title: ArrayList vs LinkedList perf?