array

Two Sum

Two Sum is solved fastest by storing seen values in a hash map and checking each number's needed complement once.

Median of Two Sorted Arrays

Find the median of two sorted arrays using binary search for efficient O(log(min(m, n))) time complexity.

Container With Most Water

Find two vertical lines that can form a container with the most water in a given array of heights.

Longest Common Prefix

Find the longest common prefix in an array of strings, returning an empty string if none exists.

3Sum

Given an integer array, return all unique triplets where the sum is zero using two-pointer scanning with careful duplica…

3Sum Closest

Find the sum of three integers in an array that is closest to a given target using two-pointer scanning.

4Sum

The 4Sum problem requires finding all unique quadruplets in an array that sum to a specific target value.

Remove Duplicates from Sorted Array

Learn how to remove duplicates from a sorted array in-place using two-pointer scanning while preserving element order.

Remove Element

Remove Element challenges you to remove a value from an array in-place using efficient two-pointer scanning and tracking…

Next Permutation

Next Permutation is a medium-difficulty problem focusing on generating the next lexicographically greater permutation of…

Search in Rotated Sorted Array

Find the index of a target in a rotated sorted array using a careful binary search that handles pivot shifts.

Find First and Last Position of Element in Sorted Array

Locate the first and last index of a target in a sorted array using binary search for precise O(log n) performance.

Search Insert Position

Find the correct index for a target value in a sorted array using binary search, or return the position where it should …

Valid Sudoku

Check if a 9x9 Sudoku board is valid by scanning rows, columns, and sub-boxes with hash lookups, ensuring no duplicates …

Sudoku Solver

Solve the Sudoku puzzle by filling empty cells while respecting Sudoku's rules using array scanning and backtracking.

Combination Sum

Find all unique combinations of numbers from a distinct array that sum to a target using controlled backtracking search.

Combination Sum II

Find all unique combinations of numbers that sum to a target using backtracking with careful pruning to avoid duplicates…

First Missing Positive

Identify the smallest missing positive integer in an unsorted array using constant space and linear time scanning techni…

Trapping Rain Water

Calculate the total trapped rain water using the elevation map array, leveraging dynamic programming and two-pointer pat…

Jump Game II

Jump Game II requires finding the minimum jumps to reach the end of an array using dynamic programming and greedy techni…

Permutations

Generate all possible orderings of a distinct integer array using backtracking search with careful pruning to avoid dupl…

Permutations II

Generate all unique permutations of an array containing duplicates using backtracking and pruning to avoid repeated sequ…

Rotate Image

Rotate an n x n matrix 90 degrees clockwise in-place using array manipulation and mathematical indexing techniques effic…

Group Anagrams

Group the anagrams in a list of strings using efficient hash table-based methods, focusing on array scanning.