Freaks City

Problem Statement Given a list accounts where each element accounts[i] is a list of strings, the first element accounts[i][0] is a name, and the remaining elements are email addresses belonging to that account. The goal is to merge accounts. Two accounts belong to the same person if they share atleast one email address. Note that accounts with ...

Problem Overview When working with numerical data structures, a common algorithmic challenge involves adding two non-negative integers represented as singly linked lists. In this specific arrangement, each node stores a single digit, and the digits are stored in reverse order (least significant digit at the head). The objective is to compute th ...

Single Number Given a non-empty array of integers where every element appears twice except for one, find that single one using bitwise XOR. The XOR operation has two critical properties: commutativity (a ^ b == b ^ a) and identity (x ^ x == 0 and x ^ 0 == x). Consequently, XORing all numbers in the array cancels out the pairs, leaving the uniqu ...

Valid Anagram A hash table can be used to efficiently determine if two strings are anagrams by counting character frequencies. By storing the frequency of each character from the first string and then decrementing the count for each character found in the second string, we can verify if all counts return to zero. class Solution { public: ...

For removing nodes with a given value, using a sentinel node avoids handling the head as a special case. A pointer starts at the sentinel and examines each successor, unlinking any node whose data matches the target. class Solution: def removeElements(self, head: Optional[ListNode], target: int) -> Optional[ListNode]: sentinel = ...

Problem Statement Write a function that calculates the quotient of two integers dividend and divisor without using the multiplication (*), division (/), or modulo (%) operators. The result should be truncated toward zero (e.g., truncate(8.345) = 8, truncate(-2.7335) = -2). Assume the environment only supports 32-bit signed inteegers, ranging fr ...

Problem Description Given a list of accounts where each account is represented as a list of strings, the first element being a name and the remaining elements being email addresses associated with that account. The task is to merge these accounts based on shared email addresses. If two accounts have at least one email in common, they belong to ...

Binary tree traversal is a fundamental operation in computer science, visiting each node in the tree in a specific order. This article covers four essential traversal methods with both recursive and iterative implementations. Preorder Traversal (Root-Left-Right) Preorder traversal visits the root node first, then the left subtree, followed by t ...

Two Sum Given an array of integers nums and a target value target, find the indices of two numbers that add up to target. Return the indices as a pair. Solution 1: Brute Force class Solution { public int[] twoSum(int[] nums, int target) { for (int i = 0; i < nums.length; i++) { for (int j = i + 1; j < nums.lengt ...

get(index): Get the value of the index-th node in the linked list. If the index is invalid, return -1. addAtHead(val): Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list. addAtTail(val): Append a node of value val as the last element of the linked lis ...