Freaks City

LeetCode 54: Spiral Matrix Problem Given an m x n matrix, return all elements of the matrix in spiral order. Example 1 Input: matrix = [[1,2,3],[4,5,6],[7,8,9]] Output: [1,2,3,6,9,8,7,4,5] Example 2 Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]] Output: [1,2,3,4,8,12,11,10,9,5,6,7] Approach Traverse from left to right along the top r ...

Problem: 24. Swap Nodes in Pairs To swap two adjacent nodes, we need a pointer standing just before the pair. A dummy sentinel node placed before the head simplifies edge cases. The traversal pointer curr starts at the sentinel. Swapping involves rerouting next pointers in three steps while preserving references that might be lost. The loop con ...

#include <bits/stdc++.h> using namespace std; class Node { public: int value; Node* next; }; bool initialize(Node*& list) { list = new Node; if (!list) return false; list->next = nullptr; return true; } bool addAtHead(Node*& list, Node* element) { if (!list || !element) return false; element-& ...

Problem Statement Given the head of a singly linked list, reverse the order of all nodes in the list and return the head of the reversed list. Sample Input 1: head = [1,2,3,4,5] Sample Output 1: [5,4,3,2,1] Sample Input 2: head = [1,2] Sample Output 2: [2,1] Sample Input 3: head = [] Sample Output 3: [] Constraints: The number of nodes i ...

Table of Contents Introduction Remove Linked List Elements (LeetCode--203) Design Linked List (LeetCode--707) Reverse Linked List (LeetCode--206) Swap Nodes in Pairs (LeetCode--24) Remove Nth Node From End of List (LeetCode--19) Linked List Cycle II (LeetCode--142) Introduction Following the Code Thinking Record series, this article explores ...

Pairwise Node Swapping in Linked List Given a linked list, swap every two adjacnet nodes and return the modified list's head. Node values must not be altered; only node positions can be chenged. Example: Input: head = [1,2,3,4] Output: [2,1,4,3] Solution: Use three pointers to manage node connections during swapping. class Solution { publi ...

Stack and Queue Fundamentals Stacks and queues share the trait that insertion and deletion occur solely at their endpoints. Typical stack storage models are sequential arrays and linked lists. A stack exhibits last-in-first-out behavior. Linked lists lack random access; elemants must be traversed sequentially. Linked representation simplifies ...

Problem DescriptionGiven the head of a linked list, determine the node where a cycle begins. If no cycle exists, return null. The cycle is identified when a node can be reached again by continuously following the next pointer. The solution must not modify the original linked list.Algorithm ExplanationFloyd's Cycle Detection Algorithm, also know ...

Structural DefinitionA headed circular doubly linked list utilizes a sentinel node (head) that acts as a starting point. Unlike a singly linked list, each node contains two pointers: prev pointing to the predecessor and next pointing to the successor. The sentinel node's prev points to the tail, and the tail's next points back to the sentinel, ...

Node Class Definition The following ListNode class serves as the foundation for all examples in this article: import java.util.Arrays; public class ListNode { int data; ListNode next = null; public ListNode(int data) { this.data = data; } public String toString(ListNode node) { int[] values = new int[calcu ...