Freaks City

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 ...

The Massage Therapist Scheduling Problem Problem link: https://leetcode.cn/problems/the-masseuse-lcci/ A renowned massage therapist receives a continuous stream of appointment requests. Each appointment can be accepted or declined. Due to the need for rest periods between sessions, she cannot accept consecutive appointments. Given a sequence of ...

Understanding Dynamic Programming Dynamic programming (DP) is an optimization technique used to solve complex problems by breaking them into simpler subproblems. It stores the results of subproblems to avoid redundant computations, thereby improving efficiency. This article explores fundamental DP concepts and implementations through various al ...

Core Principles of the 0-1 Knapsack Problem The 0-1 Knapsack Problem serves as the foundation for various packing challenges. Given a set of items with specific weights and values, the objective is to maximize value while not exceeding a given capacity constraint. Each item can be included at most once. Dynamic Programming Solution We use a DP ...

Longest Valid Parentheses Given a string containing only '(' and ')', find the length of the longest valid (well-formed and contiguous) parentheses substring. Dynamic Programming Solution Define dp[i] as the length of the longest valid parentheses ending at position i. To each character at index i: If s[i] is '(', set dp[i] = 0 If s[i] is ')', ...

Problem Description A robot is located at the top - left corner of an m x n grid (marked 'Start'). The robot can only move either down or right at any point. The goal is to reach the bottom - right corner (marked 'Finish'). We need to determine the number of unique paths possible. Examples Example 1: Input: rows = 3, cols = 7 Output: 28 Exampl ...

Trpaping Rain Water Problem Given an array representing elevation maps, this problem calculates how much water can be trapped between bars after raining. vector<int> leftMax(n, 0); vector<int> rightMax(n, 0); if (n == 0) return 0; leftMax[0] = height[0]; rightMax[n-1] = height[n-1]; for (int i = 1; i < n; ++i) { leftMax[i] = ...

Problem Analysis Given a string containing only digits within parentheses, the task is to generate all valid coordinate pairs that could have produced the original string when punctuation was removed. The coordinates must adhere to specific formatting rules: no leading or trailing zeros in decimal components, and decimal points must be preceded ...

Hash table are primarily used to store key-value mappings, enabling efficient lookups. They exemplify a time-space tradeoff—using extra memory to reduce time complexity for search operations. Two Sum Input: nums = [2,7,11,15], target = 9 Output: [0,1] Because nums[0] + nums[1] == 9. A naive approach uses nested loops, resulting in O(n²) time co ...