Efficient Binary Search in Sorted 2D Matrix
The given matrix is ordered both row-wise and column-wise, enabling a two-step binary search approach for efficient target lookup.
First, determine the correct row by comparing the first element of each row with the target. Use binary search to narrow down the candidate row where the target could reside. Once the row is identified, perform anot ...
Posted on Sun, 30 Aug 2026 16:54:26 +0000 by witt
LeetCode 414 Third Maximum Number
Given a non-empty integer array, return the third distinct maximum number in this array. If the third maximum does not exist, return the maximum number in the array.
Example 1:
Input: [3, 2, 1]
Output: 1
Explanation: The third distinct maximum is 1.
Example 2:
Input: [1, 2]
Output: 2
Explanation: The third distinct maximum does not exist, so t ...
Posted on Thu, 27 Aug 2026 16:20:00 +0000 by nepzap2
Two Sum II - Input Array Is Sorted
You are given a 1-indexed array of integers numbers that is already sorted in non-decreasing order. Find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length.
Return the indices of the two numbers, index1 and index2, as a ...
Posted on Tue, 25 Aug 2026 16:09:18 +0000 by scoman
Merging User Accounts with Disjoint Set Union and Email Mapping
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 ...
Posted on Fri, 21 Aug 2026 16:15:37 +0000 by bruceg
Implementing Linked List Addition for Reverse-Order Digits in Java
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 ...
Posted on Sun, 16 Aug 2026 16:57:59 +0000 by oskom
Algorithmic Techniques for Common LeetCode Problems
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 ...
Posted on Sat, 15 Aug 2026 16:45:20 +0000 by healthbasics
Hash Tables in Algorithmic Problem Solving: A Practical Guide
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:
...
Posted on Thu, 13 Aug 2026 16:01:30 +0000 by djjamiegee
Solving Common Linked List Problems on LeetCode: Deletion, Reversal, and Custom Implementation
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 = ...
Posted on Sun, 09 Aug 2026 16:49:44 +0000 by mrgym
Implementing Integer Division Without Multiplication or Division in JavaScript
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 ...
Posted on Fri, 07 Aug 2026 16:21:48 +0000 by mooler
Account Merging with Union-Find Data Structure
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 ...
Posted on Wed, 05 Aug 2026 16:32:12 +0000 by arya202