Freaks City

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 ...

Given a string s and an integer k, the objective is to determine the highest possible count of vowel letters within any contiguous substring of length k. Vowel letters are defined as 'a', 'e', 'i', 'o', 'u'. A sliding window approach provides an efficient solution. The algorithm first calculates the vowel count in the initial window of size k. ...

Core Concept of Dynamic Programming Dynamic Programming (DP) is an algorithmic technique used when a problem exhibits overlapping subproblems and optimal substructure. Unlike greedy algorithms—which make locally optimal choices without considering previous states—DP builds solutions incrementally, where each state is derived from one or more pr ...

House Robber I - Linear Array Problem The classic House Robber problem involves maximizing the amount of money that can be stolen from a line of houses, where adjacent houses cannot be robbed on the same night. class Solution { public: int maxLoot(vector<int>& values) { int houseCount = values.size(); if (houseCoun ...

39. Combination Sum Problem: https://leetcode.cn/problems/combination-sum/description/ Find all unique combinations of candidates where the chosen numbers sum to target. The same number may be used a unlimited number of times. class Solution { public: vector<vector<int>> combinationSum(vector<int>& candidates, int targ ...

Given an integer array nums, construct a 2D array that satisfies the following conditions: The 2D array should contain only elements from the array nums. Each row of the 2D array must consist of distinct itnegers. The number of rows should be minimized. Return any valid result. If multiple solutions exist, any one is acceptable. Note: Rows in ...

Given two singly-linked lists that are already sorted in ascending order, produce a single sorted linked list that interleaves all node from both input lists. Examples Input: list1 = [1, 2, 4], list2 = [1, 3, 4] Output: [1, 1, 2, 3, 4, 4] Input: list1 = [], list2 = [] Output: [] Input: list1 = [], list2 = [0] Output: [0] Implementation strate ...

Minimal Absolute Difference in BST Since an in-order traversal of a binary search tree produces a sorted sequence, the smallest absolute difference between any two nodes corresponds to the minimal gap between adjacent elements in this sequence. The strategy involves tracking the previously visited node and comparing its value with the current n ...

203. Remove Linked List Elements Given the head of a linked list and an integer val, remove all nodes with value equal to val and return the new head. public ListNode removeElements(ListNode head, int val) { while (head != null && head.val == val) { head = head.next; } if (head == null) return null; ListNode pre ...