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Practice › LeetCode › LeetCode 36xx ›

LeetCode 3615 - Longest Palindromic Path in Graph

LeetCode Problem 3615 Difficulty: 🔴 Hard Topics: String, Dynamic Programming, Bit Manipulation, Graph Theory, Bitmask Solution Problem Understanding We are given an undirected graph with n ≤ 14 vertices. Each vertex has a character label. We may choose any simple path in the graph, meaning a sequence of adjacent vertices in which no vertex is visited more than once. If the labels encountered along that path form a palindrome, the...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3539 - Find Sum of Array Product of Magical Sequences

LeetCode Problem 3539 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Combinatorics, Bitmask Solution Problem Understanding This problem asks us to compute the sum of array products for all magical sequences of a given length. A magical sequence is defined as a sequence of indices into the input array nums of length m , such that when you sum 2 raised to each element of the sequence, the...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3594 - Minimum Time to Transport All Individuals

LeetCode Problem 3594 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Graph Theory, Heap (Priority Queue), Shortest Path, Bitmask Solution Problem Understanding This problem is a shortest-path optimization over a highly constrained state space where you are repeatedly moving groups of people across a river using a single boat. The twist is that the travel time is not fixed: it depends both on the slowest person in the group and on...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3533 - Concatenated Divisibility

LeetCode Problem 3533 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution LeetCode 3533 - Concatenated Divisibility Problem Understanding We are given an array nums containing up to 13 positive integers and an integer k . We may reorder the numbers in any permutation. After choosing an ordering, we concatenate the decimal representations of the numbers to form a single large integer. The task is to find a...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3530 - Maximum Profit from Valid Topological Order in DAG

LeetCode Problem 3530 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Graph Theory, Topological Sort, Bitmask Solution Problem Understanding The problem requires computing the maximum possible profit achievable by processing nodes of a Directed Acyclic Graph (DAG) in a valid topological order . Each node has a score, and the profit contribution of a node is its score multiplied by its position in the processing order (1-based). The goal...

Practice › LeetCode › LeetCode 34xx ›

LeetCode 3444 - Minimum Increments for Target Multiples in an Array

LeetCode Problem 3444 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Number Theory, Bitmask Solution LeetCode 3444 - Minimum Increments for Target Multiples in an Array Problem Understanding We are given two arrays: nums , the array whose elements we are allowed to increase. target , a small array containing values that must each be represented by at least one multiple somewhere in the final version of nums...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3376 - Minimum Time to Break Locks I

LeetCode Problem 3376 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Breadth-First Search, Bitmask Solution LeetCode 3376 - Minimum Time to Break Locks I Problem Understanding The problem describes a sequence of locks that must all be broken. Each lock requires a certain amount of energy, given by strength[i] . Bob's sword starts with: Energy = 0 Growth factor x = 1 Every minute, the sword gains x...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2152 - Minimum Number of Lines to Cover Points

LeetCode Problem 2152 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Dynamic Programming, Backtracking, Bit Manipulation, Geometry, Bitmask Solution Problem Understanding This problem asks us to determine the minimum number of straight lines needed to cover a given set of points on an X-Y plane. Each point is defined by its (x, y) coordinates, and a straight line can pass through any number of points as long as they are...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2572 - Count the Number of Square-Free Subsets

LeetCode Problem 2572 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Bit Manipulation, Number Theory, Bitmask Solution Problem Understanding The problem asks us to count all non-empty subsets of a given array nums such that the product of the elements in each subset is square-free . A square-free integer is an integer not divisible by the square of any prime greater than 1. In other words, in its prime factorization,...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3003 - Maximize the Number of Partitions After Operations

LeetCode Problem 3003 Difficulty: 🔴 Hard Topics: String, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to take a string s and an integer k and compute the maximum number of partitions we can create from s under a specific set of operations. First, we are allowed to change at most one character in the string to any other lowercase English letter. After that, we repeatedly...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2741 - Special Permutations

LeetCode Problem 2741 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to count the number of special permutations of a given array of distinct positive integers nums . A permutation is special if, for every adjacent pair of elements nums[i] and nums[i+1] , one element divides the other evenly, that is, either nums[i] % nums[i+1] == 0 or nums[i+1] % nums[i]...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1947 - Maximum Compatibility Score Sum

LeetCode Problem 1947 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem is asking us to optimally pair students with mentors such that the sum of their compatibility scores is maximized. Each student and each mentor has answered n yes/no questions represented by 0 s and 1 s. A student-mentor pair's compatibility score is the count of matching answers. For instance, if a...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1994 - The Number of Good Subsets

LeetCode Problem 1994 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Dynamic Programming, Bit Manipulation, Counting, Number Theory, Bitmask Solution LeetCode 1994 - The Number of Good Subsets Problem Understanding This problem asks us to count how many subsets of the input array have a product that can be written as a multiplication of distinct prime numbers. The phrase "distinct prime numbers" is the key restriction. A product is valid...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2172 - Maximum AND Sum of Array

LeetCode Problem 2172 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution LeetCode 2172 - Maximum AND Sum of Array Problem Understanding This problem asks us to distribute a set of integers into numbered slots in a way that maximizes a scoring function based on bitwise AND operations. We are given: An integer array nums A number of slots, numSlots Each slot is numbered from 1 to numSlots...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2992 - Number of Self-Divisible Permutations

LeetCode Problem 2992 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Backtracking, Bit Manipulation, Number Theory, Bitmask Solution Problem Understanding The problem asks us to count how many permutations of the numbers 1 through n satisfy a special condition called self-divisible. We start with the array: [1, 2, 3, ..., n] We must rearrange these numbers into every possible permutation, then determine whether the permutation is valid. A permutation a...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3276 - Select Cells in Grid With Maximum Score

LeetCode Problem 3276 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Matrix, Bitmask Solution Problem Understanding The problem requires us to select cells from a 2D matrix grid such that no two selected cells are in the same row, and all selected values are unique. Our goal is to maximize the sum of these selected values. In other words, for each row, we can choose at most one value,...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3283 - Maximum Number of Moves to Kill All Pawns

LeetCode Problem 3283 Difficulty: 🔴 Hard Topics: Array, Math, Bit Manipulation, Breadth-First Search, Game Theory, Bitmask Solution Problem Understanding The problem gives us a 50 x 50 chessboard containing exactly one knight and up to 15 pawns. The knight starts at position (kx, ky) , and every pawn is placed at one of the coordinates in positions . Two players, Alice and Bob, alternate turns. Alice moves first. During a...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1879 - Minimum XOR Sum of Two Arrays

LeetCode Problem 1879 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to take two integer arrays of equal length, nums1 and nums2 , and rearrange the elements of nums2 to minimize the XOR sum . The XOR sum is computed as (nums1[0] XOR nums2[0]) + (nums1[1] XOR nums2[1]) + ... + (nums1[n - 1] XOR nums2[n - 1]) . The task...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2305 - Fair Distribution of Cookies

LeetCode Problem 2305 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to distribute a set of cookie bags among k children such that the unfairness of the distribution is minimized. Here, unfairness is defined as the maximum total number of cookies any single child receives . The input consists of an array cookies where cookies[i] represents the number of cookies...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2850 - Minimum Moves to Spread Stones Over Grid

LeetCode Problem 2850 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Matrix, Bitmask Solution Problem Understanding This problem asks us to take a 3x3 grid of integers representing stones in each cell and redistribute them so that every cell contains exactly one stone. Each move consists of moving a stone from one cell to a directly adjacent cell (sharing a side, not a diagonal). The goal is to...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2247 - Maximum Cost of Trip With K Highways

LeetCode Problem 2247 Difficulty: 🔴 Hard Topics: Dynamic Programming, Bit Manipulation, Graph Theory, Bitmask Solution Problem Understanding The problem gives us an undirected weighted graph with n cities and a list of highways. Each highway connects two cities and has an associated toll cost. We must find the maximum possible total toll for a trip that uses exactly k highways. There are two important restrictions: We may start from any...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2184 - Number of Ways to Build Sturdy Brick Wall

LeetCode Problem 2184 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to compute the number of ways to build a wall of given height and width using bricks of specified widths, such that the wall is sturdy . A wall is sturdy if no two adjacent rows have bricks that meet at the same position horizontally, except at the ends of...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1986 - Minimum Number of Work Sessions to Finish the Tasks

LeetCode Problem 1986 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding This problem asks us to schedule a collection of tasks into the minimum number of work sessions. Each task has a fixed duration, and every work session has a maximum allowed length, sessionTime . A task cannot be split across multiple sessions. Once a task starts inside a session, it must fully complete...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3149 - Find the Minimum Cost Array Permutation

LeetCode Problem 3149 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem presents an array nums of length n that is a permutation of integers from 0 to n - 1 . We are asked to find a permutation perm of the same range [0, 1, 2, ..., n-1] that minimizes a special cost function defined as: $$\text{score}(perm) = |perm[0] - nums[perm[1]]| + |perm[1]...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2403 - Minimum Time to Kill All Monsters

LeetCode Problem 2403 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem is asking us to compute the minimum number of days required to defeat all monsters in an array power , where power[i] represents the strength of the i-th monster. You start with zero mana and gain mana daily, with the initial daily gain of 1 . After defeating a monster, your mana...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2002 - Maximum Product of the Length of Two Palindromic Subsequences

LeetCode Problem 2002 Difficulty: 🟡 Medium Topics: String, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem is asking us to find two disjoint palindromic subsequences from a given string s such that the product of their lengths is maximized. A subsequence is derived by deleting zero or more characters from the original string while keeping the relative order intact. A palindrome reads the same forward and backward,...

Practice › LeetCode › LeetCode 13xx ›

LeetCode 1349 - Maximum Students Taking Exam

LeetCode Problem 1349 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Matrix, Bitmask Solution LeetCode 1349 is long and detailed enough that a complete high quality guide with all required sections, full prose explanations, worked examples, corrected Python and Go implementations, exhaustive test cases, and edge case analysis will exceed a single response limit if done properly. I can provide the full reference-quality guide in consecutive parts , while...

Practice › LeetCode › LeetCode 17xx ›

LeetCode 1755 - Closest Subsequence Sum

LeetCode Problem 1755 Difficulty: 🔴 Hard Topics: Array, Two Pointers, Dynamic Programming, Bit Manipulation, Sorting, Bitmask Solution Problem Understanding The problem asks us to find a subsequence of a given integer array nums such that the sum of that subsequence is as close as possible to a given integer goal . A subsequence can include any subset of elements in their original order, including the possibility of selecting none (which...

Practice › LeetCode › LeetCode 08xx ›

LeetCode 805 - Split Array With Same Average

LeetCode Problem 805 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks whether we can divide the given array nums into two non-empty groups such that both groups have the same average. Suppose the array is split into subsets A and B . Let: sum(A) be the sum of elements in A len(A) be the number of elements in A...

Practice › LeetCode › LeetCode 04xx ›

LeetCode 473 - Matchsticks to Square

LeetCode Problem 473 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution LeetCode 473 - Matchsticks to Square Problem Understanding The problem gives us an array called matchsticks , where each element represents the length of a matchstick. The goal is to determine whether all of the matchsticks can be arranged to form exactly one square. A square has four equal sides, so the total length of...

Practice › LeetCode › LeetCode 17xx ›

LeetCode 1723 - Find Minimum Time to Finish All Jobs

LeetCode Problem 1723 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding This problem is asking us to assign a set of jobs, each with a specific time requirement, to k workers such that every job is assigned to exactly one worker, and we minimize the maximum total working time among all workers. The input jobs is an integer array where jobs[i] represents the time...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1659 - Maximize Grid Happiness

LeetCode Problem 1659 Difficulty: 🔴 Hard Topics: Dynamic Programming, Bit Manipulation, Memoization, Bitmask Solution Problem Understanding This problem asks us to place introverts and extroverts inside an m x n grid in a way that maximizes the total happiness score. Every grid cell can either remain empty, contain one introvert, or contain one extrovert. We are allowed to leave some people unused, so we do not necessarily have to place...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1655 - Distribute Repeating Integers

LeetCode Problem 1655 Difficulty: 🔴 Hard Topics: Array, Hash Table, Dynamic Programming, Backtracking, Bit Manipulation, Counting, Bitmask Solution Problem Understanding This problem asks whether we can satisfy a set of customer requests using repeated integers from the array nums . Each customer wants a certain quantity of numbers, given by quantity[i] . The important restriction is that every number given to a single customer must be identical. A customer asking...

Practice › LeetCode › LeetCode 11xx ›

LeetCode 1125 - Smallest Sufficient Team

LeetCode Problem 1125 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding This problem asks us to build the smallest possible team that collectively covers every required skill. We are given two inputs: req_skills , a list of unique required skills people , where people[i] contains the skills possessed by person i A team is considered sufficient if every skill in req_skills appears in at least...

Practice › LeetCode › LeetCode 04xx ›

LeetCode 465 - Optimal Account Balancing

LeetCode Problem 465 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem gives a list of money transfers between people. Each transaction is represented as [from, to, amount] , meaning one person paid a certain amount to another person. After all transactions are completed, some people may owe money overall, while others are owed money overall. The goal is not to recreate the...

Practice › LeetCode › LeetCode 14xx ›

LeetCode 1494 - Parallel Courses II

LeetCode Problem 1494 Difficulty: 🔴 Hard Topics: Dynamic Programming, Bit Manipulation, Graph Theory, Bitmask Solution Problem Understanding The problem asks us to determine the minimum number of semesters required to complete n courses when there are prerequisite constraints between some courses and a limit k on the number of courses that can be taken in a single semester. The input consists of an integer n , a list of prerequisite...

Practice › LeetCode › LeetCode 06xx ›

LeetCode 698 - Partition to K Equal Sum Subsets

LeetCode Problem 698 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask Solution Problem Understanding The problem is asking whether an array of integers nums can be divided into exactly k subsets such that each subset has the same sum. The input consists of the integer array nums and the integer k . The expected output is a boolean value: true if such a partitioning is possible,...

Practice › LeetCode › LeetCode 05xx ›

LeetCode 526 - Beautiful Arrangement

LeetCode Problem 526 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to count how many permutations of the integers from 1 to n satisfy a special divisibility condition. A permutation is an arrangement of all numbers from 1 to n where every number appears exactly once. For example, when n = 3 , the possible permutations include [1,2,3] , [2,1,3]...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1815 - Maximum Number of Groups Getting Fresh Donuts

LeetCode Problem 1815 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Memoization, Bitmask Solution Problem Understanding This problem asks us to maximize the number of “happy” customer groups by choosing the best possible ordering of the groups. The donut shop produces donuts in batches of exactly batchSize . A fresh batch starts only when the previous batch has been completely consumed. A group is considered happy if the very...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1617 - Count Subtrees With Max Distance Between Cities

LeetCode Problem 1617 Difficulty: 🔴 Hard Topics: Dynamic Programming, Bit Manipulation, Tree, Enumeration, Bitmask Solution Problem Understanding The input describes an undirected tree with n cities. Since the graph is a tree, there are exactly n - 1 edges and there is a unique simple path between every pair of cities. The problem asks us to examine every possible connected subset of cities. A subset is considered a valid subtree...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1681 - Minimum Incompatibility

LeetCode Problem 1681 Difficulty: 🔴 Hard Topics: Array, Hash Table, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem is asking us to partition an integer array nums into exactly k subsets of equal size, such that no subset contains duplicate elements. The incompatibility of a subset is defined as the difference between its maximum and minimum values. Our goal is to find the minimum possible sum of these...

Practice › LeetCode › LeetCode 09xx ›

LeetCode 943 - Find the Shortest Superstring

LeetCode Problem 943 Difficulty: 🔴 Hard Topics: Array, String, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to find the shortest superstring that contains all the given strings in the array words as substrings. In other words, we need a single string that includes every string in words at least once, concatenated in some order, but we want this superstring to have minimal length. The problem...

Practice › LeetCode › LeetCode 06xx ›

LeetCode 638 - Shopping Offers

LeetCode Problem 638 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask Solution Problem Understanding This problem asks us to find the minimum cost to buy a set of items given individual prices and optional special offers. We are given three main inputs: an array price that specifies the unit price for each item, an array needs that specifies the exact number of each item we want...

Practice › LeetCode › LeetCode 04xx ›

LeetCode 464 - Can I Win

LeetCode Problem 464 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming, Bit Manipulation, Memoization, Game Theory, Bitmask Solution LeetCode 464 - Can I Win Problem Understanding This problem describes a two-player turn-based game. Players take turns choosing a number from a shared pool of integers ranging from 1 to maxChoosableInteger . Once a number is chosen, it cannot be used again for the rest of the game. Each chosen number is...

Practice › LeetCode › LeetCode 09xx ›

LeetCode 996 - Number of Squareful Arrays

LeetCode Problem 996 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to count all permutations of a given integer array nums such that the array is squareful , meaning that the sum of every pair of adjacent elements is a perfect square . In other words, for a permutation [a1, a2, a3, ..., an] , each a[i]...

Practice › LeetCode › LeetCode 06xx ›

LeetCode 691 - Stickers to Spell Word

LeetCode Problem 691 Difficulty: 🔴 Hard Topics: Array, Hash Table, String, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask Solution Let's dive deep into a detailed technical solution guide for LeetCode 691, following your formatting rules exactly. Problem Understanding The problem asks us to construct a target string using letters cut from an unlimited supply of given stickers, where each sticker is a lowercase word. You can reuse stickers multiple times...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference

LeetCode Problem 2035 Difficulty: 🔴 Hard Topics: Array, Two Pointers, Binary Search, Dynamic Programming, Bit Manipulation, Sorting, Ordered Set, Bitmask Solution Problem Understanding The problem gives an array nums containing exactly 2 * n integers. We must divide these integers into two separate groups, each containing exactly n elements. After forming the two groups, we compute the sum of each group and measure the absolute difference between those sums. Our...

Practice › LeetCode › LeetCode 10xx ›

LeetCode 1066 - Campus Bikes II

LeetCode Problem 1066 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution That is a long-form technical guide with multiple required sections and detailed worked examples. I can provide the complete reference document, but it will be quite lengthy. I will include all requested sections: Problem Understanding Brute Force and Optimal Approaches Comparison Table Step-by-step Algorithm Walkthrough with proof sketch Complete Python Solution Complete Go Solution Fully...

Practice › LeetCode › LeetCode 08xx ›

LeetCode 847 - Shortest Path Visiting All Nodes

LeetCode Problem 847 Difficulty: 🔴 Hard Topics: Dynamic Programming, Bit Manipulation, Breadth-First Search, Graph Theory, Bitmask Solution Problem Understanding The problem gives us an undirected and connected graph with n nodes labeled from 0 to n - 1 . The graph is represented as an adjacency list, where graph[i] contains all nodes directly connected to node i . We must compute the length of the shortest path that visits every...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 351 - Android Unlock Patterns

LeetCode Problem 351 Difficulty: 🟡 Medium Topics: Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem models the Android lock screen as a 3 x 3 grid containing digits 1 through 9 . A valid unlock pattern is a sequence of distinct dots that follows a special movement rule. The first rule is straightforward: each dot can only be used once in a pattern. This means every pattern...

Practice › LeetCode › LeetCode 14xx ›

LeetCode 1434 - Number of Ways to Wear Different Hats to Each Other

LeetCode Problem 1434 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution LeetCode 1434 - Number of Ways to Wear Different Hats to Each Other Problem Understanding This problem asks us to count how many valid ways exist to assign hats to people under two constraints: Every person must receive exactly one hat they like. No two people may wear the same hat. The input is a 2D...

Practice › LeetCode › LeetCode 12xx ›

LeetCode 1255 - Maximum Score Words Formed by Letters

LeetCode Problem 1255 Difficulty: 🔴 Hard Topics: Array, Hash Table, String, Dynamic Programming, Backtracking, Bit Manipulation, Counting, Bitmask Solution Problem Understanding This problem asks us to select a subset of words that can be constructed using a limited supply of letters, such that the total score of all chosen words is maximized. We are given three inputs: words , an array of strings letters , a multiset of available characters...

Practice › LeetCode › LeetCode 15xx ›

LeetCode 1595 - Minimum Cost to Connect Two Groups of Points

LeetCode Problem 1595 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Matrix, Bitmask Solution Problem Understanding The problem is asking us to find the minimum cost to connect two groups of points, where the first group has size1 points and the second group has size2 points. We are given a cost matrix cost of size size1 x size2 where cost[i][j] represents the cost of connecting the i -th point...

Practice › LeetCode › LeetCode 17xx ›

LeetCode 1799 - Maximize Score After N Operations

LeetCode Problem 1799 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Backtracking, Bit Manipulation, Number Theory, Bitmask Solution Problem Understanding The problem asks us to maximize the total score obtained by performing n operations on an array nums of size 2 * n . In each operation, you select two elements from the array, calculate the greatest common divisor (GCD) of the two elements, multiply it by the operation index...

Practice › LeetCode › LeetCode (archived) › LeetCode 10xx ›

LeetCode 1066: Campus Bikes II

Problem Restatement We have n workers and m bikes on a campus. We need to assign each worker exactly one bike, minimizing the total Manhattan distance between each worker and their assigned bike. Return the minimum total Manhattan distance. The official constraints state that n <= m <= 10 (small, bitmask DP is feasible). Input and Output Item Meaning Input Worker positions and bike positions Output Minimum total assignment distance...

Practice › LeetCode › LeetCode (archived) › LeetCode 08xx ›

LeetCode 847: Shortest Path Visiting All Nodes

Problem Restatement We are given an undirected connected graph with n nodes labeled from 0 to n - 1 . The graph is given as an adjacency list: graph[i] contains all nodes directly connected to node i . We need to return the length of the shortest path that visits every node at least once. Important details: Rule Meaning Start We may start at any node End We may stop...

Practice › LeetCode › LeetCode (archived) › LeetCode 09xx ›

LeetCode 943: Find the Shortest Superstring

Problem Restatement We are given an array of strings: words We need to return the shortest string that contains every string in words as a substring. If several shortest answers exist, we may return any of them. The problem also says that no string in words is a substring of another string in words . This lets us focus on ordering and overlapping the strings, instead of removing already-contained strings....

Practice › LeetCode › LeetCode (archived) › LeetCode 08xx ›

LeetCode 864: Shortest Path to Get All Keys

Problem Restatement We are given a 2D grid. Each cell contains one character: Character Meaning "." Empty cell "#" Wall "@" Starting position "a" to "f" Key "A" to "F" Lock We start at "@" . One move means walking one cell up, down, left, or right. We cannot walk outside the grid. We cannot walk through walls. When we step on a key, we pick it up. We cannot...

Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 698: Partition to K Equal Sum Subsets

Problem Restatement We are given an integer array nums and an integer k . We need to return true if it is possible to divide nums into k non-empty subsets such that every subset has the same sum. Otherwise, return false . Each number must be used exactly once. The official constraints include 1 <= k <= nums.length <= 16 and positive integers in nums . ( leetcode.com ) Input...

Practice › LeetCode › LeetCode (archived) › LeetCode 06xx ›

LeetCode 691: Stickers to Spell Word

Problem Restatement We are given a list of sticker words and a target string. Each sticker contains lowercase English letters. We may cut letters from stickers and rearrange them to form the target. We have infinite copies of every sticker, so the same sticker type can be used more than once. Return the minimum number of stickers needed to form target . If it is impossible, return -1 . The...

Practice › LeetCode › LeetCode (archived) › LeetCode 05xx ›

LeetCode 526: Beautiful Arrangement

Problem Restatement We are given an integer n . There are n integers labeled from 1 to n . We need to count how many permutations of these numbers are beautiful. A permutation perm is beautiful if, for every position i , at least one of these is true: perm[i] % i == 0 or: i % perm[i] == 0 The permutation is 1-indexed. That means positions start from 1...

Practice › LeetCode › LeetCode (archived) › LeetCode 04xx ›

LeetCode 473: Matchsticks to Square

Problem Restatement We are given an integer array matchsticks . Each value represents the length of one matchstick. We must use every matchstick exactly once. We need to determine whether all matchsticks can form a square. A square has four sides of equal length, so the task is to divide the matchsticks into four groups with the same sum. The official problem asks whether the given matchsticks can make one...

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LeetCode 464: Can I Win

Problem Restatement We are given two integers: maxChoosableInteger desiredTotal There are numbers from 1 to maxChoosableInteger . Two players take turns choosing one unused number. Each chosen number is added to a running total. The player who makes the running total reach or exceed desiredTotal wins. Both players play optimally. We need to return whether the first player can force a win. The official problem asks whether the first player...

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