README.md

Linked List

Singly and doubly linked list manipulation and algorithms.

Key Concepts Covered

• Linked list design and implementation
• Two-pointer technique (fast/slow pointers)
• List reversal
• Cycle detection (Floyd's algorithm)
• Merging sorted lists
• Partitioning lists
• Deep copy with random pointers
• Doubly linked lists (DLL)

Problems in this Directory

Basic Implementation

• ll_design_linked_list - Basic linked list design
• ll_insertdeleteprint - Insert, delete, print operations
• ll_basic - Linked list basics
• ll_linkedlist - Linked list implementation
• ll_ver2 - Linked list version 2
• linkedlist - Linked list implementation
• LinkedListClass - Linked list class
• LinkedListInsertDeletePrint - Insert/delete/print
• cyclicQueue - Circular queue using linked list
• myStack - Stack implementation using linked list

Reversal Problems

• ll_reverse_between - Reverse portion of list
• ll_reverse_b2c - Reverse between positions
• ll_reverselist_kgroups - Reverse in K groups
• ll_swap_pairs - Swap adjacent nodes

Merging & Sorting

• ll_mergesorted - Merge two sorted lists
• MergeSorrtedLL - Merge sorted linked lists
• mergeKsortedLL - Merge K sorted lists
• SortLinkedList - Sort linked list

List Manipulation

• ll_partition_list - Partition by value
• ll_remove_dupl - Remove duplicates
• ll_binary2_decci - Binary to decimal conversion
• deletenthNodefromLastLL - Delete nth node from end
• getMiddleNodeLL - Get middle node (fast/slow pointers)

Advanced Problems

• ll_clonelinked_list - Deep copy with random pointers
• palindromeLinkedlist - Check if palindrome
• intersectionofLL - Find intersection of two lists
• RemoveLoopLinkedList - Detect and remove cycle

Doubly Linked List (DLL)

• dll_design - Doubly linked list design
• dll_reverse - Reverse DLL
• dll_is_palindrome - Check if DLL is palindrome
• dll_swap_pairs - Swap pairs in DLL
• dll_swap_first_last - Swap first and last nodes
• doublyLinkedList - DLL implementation

LRU Cache

• LRU_LinkedList - LRU Cache using linked list
• LRU_UmapLL - LRU using unordered_map and linked list

Special Problems

• SingleNumber - Find single number
• SingleNumberIII - Find two single numbers
• SingleNumber3set - Single number (3 sets)
• SingleElement_BS - Single element using binary search
• Nby3Times - N/3 times problem
• repeatedChar - Find repeated character
• deserializeLevelOrderTree - Deserialize level order tree

Tips

• Always handle NULL pointers carefully
• Draw diagrams for pointer manipulation
• Use dummy nodes to simplify edge cases
• Practice reversing lists—it's fundamental
• Remember to update all pointers in DLL