剑指offer

Generate all string permutations using recursive backtracking, deduplicate them, and sort them lexicographically.

Use the Fibonacci recurrence to calculate the number of ways a frog can climb the stairs.

Derive the number of ways to climb stairs when each jump may cover any number of steps using a recurrence and a pattern.

Record three implementations of the Fibonacci sequence: recursion, memoization, and dynamic programming.

Count the number of 1 bits in a 32-bit binary representation by shifting through each bit.

Calculate a floating-point number raised to an integer power using repeated multiplication, including negative exponents.

Enumerate integers and use modulo operations to count occurrences of digit 1 in decimal representations from 1 to n.

Use a map to count character occurrences while preserving input order to find the first character that appears only once in a stream.

Record two implementations of cyclic left rotation of a string: slicing and concatenation, and three reversals.

Sort five cards, treat jokers as 0, and use the gaps between non-zero cards to determine whether they can form a straight.

Record two implementations for replacing spaces with %20: character-by-character concatenation and preallocated storage.

Record recursive and stack-based methods for outputting a linked list from tail to head.

Record stack-based and three-pointer implementations for reversing a singly linked list.

Record iterative and recursive implementations for merging two sorted linked lists.

Record array, length-conversion, and fast-slow-pointer methods for finding the k-th node from the end.

Record the method of copying a complex linked list by inserting copied nodes after the original nodes.

Record set-based and fast/slow-pointer methods for finding the entry node of a linked-list cycle.

Record a two-pointer method that uses the length difference to find the first common node of two linked lists.

Record counting- and set-based methods for deleting all duplicate nodes from a sorted linked list.

Record a recursive method for determining whether a sequence is the postorder traversal result of a binary search tree.

Record methods for finding the inorder successor of a binary-tree node through a full inorder traversal or parent-pointer relationships.

Record inorder-traversal and recursive methods for converting a binary search tree into a sorted doubly linked list.

Record inorder-traversal methods for finding the kth smallest node in a binary search tree, plus reverse inorder traversal for the kth largest node.

Record a recursive method for computing binary-tree depth by taking the greater depth of the left and right subtrees.

Record queue-based level-order traversal for printing binary-tree nodes from top to bottom.

Record a recursive method for determining whether a binary tree is symmetric by comparing mirrored positions in its left and right subtrees.

Record a method for determining whether a binary tree is balanced by comparing subtree heights and recursively checking both subtrees.

Record recursive, stack-based, and queue-based methods for generating the mirror of a binary tree by swapping left and right subtrees.

Record a queue-based method that uses end-of-line pointers to print a binary tree level by level, one line per level.

Record a zigzag traversal method by reversing alternating rows after level-order traversal.

Record a preorder-recursive matching method for determining whether one binary tree is a substructure of another.

Record the recursive method for reconstructing a binary tree from preorder and inorder traversal results.

Record the depth-first, preorder traversal, and backtracking method for finding binary-tree paths with a given sum.

Record methods for serializing and deserializing a binary tree using preorder traversal and a preorder-plus-inorder traversal combination.

Record character parsing and atoi implementations for converting a string to an integer.

Record methods for reversing word order by splitting the string and by reversing twice.

Record using an auxiliary minimum stack to retrieve the stack minimum in O(1) time.

Record methods that use an auxiliary stack to determine whether a given sequence is a valid pop sequence.

Record how to implement queue Push, Pop, Peek, and Empty operations using two stacks.

Mirror translation of the original Sword Offer note: Search in a 2D Array.

Mirror translation of the original Sword Offer note: Two Numbers with Sum S.

Mirror translation of the original Sword Offer note: Continuous Positive Sequences with Sum S.

Mirror translation of the original Sword Offer note: Last Remaining Number in a Circle.

Mirror translation of the original Sword Offer note: Arrange an Array into the Smallest Number.

Mirror translation of the original Sword Offer note: Count Occurrences in a Sorted Array.

Mirror translation of the original Sword Offer note: Number Appearing More Than Half the Time.

Mirror translation of the original Sword Offer note: Numbers Appearing Only Once.

Mirror translation of the original Sword Offer note: Inverse Pairs in an Array.

Mirror translation of the original Sword Offer note: Duplicate Number in an Array.

Mirror translation of the original Sword Offer note: Minimum Number in a Rotated Array.

Mirror translation of the original Sword Offer note: Smallest K Numbers.

Mirror translation of the original Sword Offer note: Robot Movement Range.

Mirror translation of the original Sword Offer note: Maximum in Sliding Windows.

Mirror translation of the original Sword Offer note: Reorder Array with Odd Numbers Before Even Numbers.

Mirror translation of the original Sword Offer note: Maximum Sum of a Contiguous Subarray.