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Practice › LeetCode › LeetCode 38xx ›

LeetCode 3828 - Final Element After Subarray Deletions

LeetCode Problem 3828 Difficulty: 🟡 Medium Topics: Array, Math, Brainteaser, Game Theory Solution Problem Understanding We are given an integer array nums . Two players, Alice and Bob, repeatedly remove a contiguous subarray from the current array. The only restriction is that the removed subarray cannot be the entire current array, so after every move at least one element remains. After a subarray is removed, the remaining elements are concatenated...

Practice › LeetCode › LeetCode 36xx ›

LeetCode 3674 - Minimum Operations to Equalize Array

LeetCode Problem 3674 Difficulty: 🟢 Easy Topics: Array, Bit Manipulation, Brainteaser Solution Let's go step by step and produce a fully detailed, reference-style solution guide for LeetCode 3674 following your requested formatting. Problem Understanding The problem asks us to make all elements of an integer array nums equal using the minimum number of operations. Each operation consists of selecting a contiguous subarray and replacing every element in that subarray with...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3596 - Minimum Cost Path with Alternating Directions I

LeetCode Problem 3596 Difficulty: 🟡 Medium Topics: Math, Brainteaser Solution Problem Understanding This problem requires computing the minimum total cost to traverse a grid from the top-left corner (0, 0) to the bottom-right corner (m - 1, n - 1) while following a strict alternating movement pattern. Each cell (i, j) has a cost to enter, calculated as (i + 1) * (j + 1) . Movement is constrained by...

Practice › LeetCode › LeetCode 35xx ›

LeetCode 3577 - Count the Number of Computer Unlocking Permutations

LeetCode Problem 3577 Difficulty: 🟡 Medium Topics: Array, Math, Brainteaser, Combinatorics Solution Problem Understanding The problem presents a set of n computers, each with a unique password complexity represented in an array complexity of length n . The computers are labeled 0 to n - 1 , and only computer 0 is initially unlocked. To unlock another computer i , you must already have unlocked at least one computer j...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2425 - Bitwise XOR of All Pairings

LeetCode Problem 2425 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Brainteaser Solution Problem Understanding The problem gives us two arrays, nums1 and nums2 , and asks us to compute the XOR of every possible pair formed between the two arrays. For every element in nums1 , we pair it with every element in nums2 exactly once. Each pair produces a value using the bitwise XOR operation: nums1[i] ^ nums2[j] If...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1908 - Game of Nim

LeetCode Problem 1908 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Bit Manipulation, Brainteaser, Game Theory Solution Problem Understanding This problem is the classic mathematical game known as Nim. We are given an array piles , where each element represents the number of stones in a pile. Two players, Alice and Bob, take turns removing stones. On each turn, a player may choose any non-empty pile and remove any positive...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2419 - Longest Subarray With Maximum Bitwise AND

LeetCode Problem 2419 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Brainteaser Solution Problem Understanding The problem asks us to find the length of the longest subarray within a given array nums such that the bitwise AND of all elements in that subarray is maximized . In simpler terms, we first need to identify the largest possible bitwise AND we can get from any subarray, and then determine the contiguous subarray(s)...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2745 - Construct the Longest New String

LeetCode Problem 2745 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming, Greedy, Brainteaser Solution LeetCode 2745 - Construct the Longest New String Problem Understanding The problem gives us three types of fixed two-character strings: "AA" appears x times "BB" appears y times "AB" appears z times We may choose any subset of these strings and concatenate them in any order. The goal is to build the longest possible resulting string while...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2749 - Minimum Operations to Make the Integer Zero

LeetCode Problem 2749 Difficulty: 🟡 Medium Topics: Bit Manipulation, Brainteaser, Enumeration Solution Problem Understanding The problem gives us two integers, num1 and num2 . In one operation, we may choose any integer i between 0 and 60 , inclusive, and subtract the value 2^i + num2 from num1 . The goal is to determine the minimum number of operations required to make num1 become exactly 0 . If it is...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2505 - Bitwise OR of All Subsequence Sums

LeetCode Problem 2505 Difficulty: 🟡 Medium Topics: Array, Math, Bit Manipulation, Brainteaser, Prefix Sum Solution LeetCode 2505 - Bitwise OR of All Subsequence Sums Problem Understanding This problem asks us to compute the bitwise OR of every possible subsequence sum of a given array. A subsequence is formed by choosing any subset of elements while preserving their original order. Since every element can either be included or excluded, an array...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3227 - Vowels Game in a String

LeetCode Problem 3227 Difficulty: 🟡 Medium Topics: Math, String, Brainteaser, Game Theory Solution Problem Understanding The problem describes a two-player game between Alice and Bob played on a string s . Alice always moves first. The rules for each player are based on vowel counts in substrings: Alice can remove any non-empty substring containing an odd number of vowels , while Bob can remove any non-empty substring containing an even...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2731 - Movement of Robots

LeetCode Problem 2731 Difficulty: 🟡 Medium Topics: Array, Brainteaser, Sorting, Prefix Sum Solution LeetCode 2731 - Movement of Robots Problem Understanding The problem gives us a list of robots positioned on an infinite number line. Each robot starts at a unique coordinate from the array nums , and each robot has an associated movement direction from the string s . A robot moves exactly one unit per second. If the...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2396 - Strictly Palindromic Number

LeetCode Problem 2396 Difficulty: 🟡 Medium Topics: Math, Two Pointers, Brainteaser Solution Problem Understanding The problem asks whether a given integer n is strictly palindromic . A number is strictly palindromic if, for every base b between 2 and n - 2 (inclusive), its representation in base b reads the same forwards and backwards. In simpler terms, you need to check all number systems from base 2 up to base...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2568 - Minimum Impossible OR

LeetCode Problem 2568 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Brainteaser Solution Problem Understanding The problem asks us to find the smallest positive integer that cannot be represented as a bitwise OR of any subsequence of a given array nums . The input array contains positive integers, and the subsequences can have any length, including length 1. The output must be the smallest integer greater than zero that cannot be...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 319 - Bulb Switcher

LeetCode Problem 319 Difficulty: 🟡 Medium Topics: Math, Brainteaser Solution Problem Understanding The problem describes a sequence of n bulbs, all initially turned off. We perform n rounds of operations on these bulbs. In the first round, every bulb is turned on. In the second round, every second bulb is toggled, meaning on bulbs become off and off bulbs become on. In the third round, every third bulb is toggled,...

Practice › LeetCode › LeetCode 15xx ›

LeetCode 1503 - Last Moment Before All Ants Fall Out of a Plank

LeetCode Problem 1503 Difficulty: 🟡 Medium Topics: Array, Brainteaser, Simulation Solution Problem Understanding The problem describes a plank of length n on which ants are walking either to the left or to the right at a constant speed of 1 unit per second. We are given two arrays: left contains the starting positions of ants moving left, and right contains the starting positions of ants moving right. When two ants...

Practice › LeetCode › LeetCode 10xx ›

LeetCode 1025 - Divisor Game

LeetCode Problem 1025 Difficulty: 🟢 Easy Topics: Math, Dynamic Programming, Brainteaser, Game Theory Solution Problem Understanding The problem describes a two-player turn-based game between Alice and Bob. The game starts with a single integer n written on a chalkboard. Alice always takes the first turn. On each turn, the current player must choose a positive integer x such that: 0 < x < n x divides n evenly, meaning n...

Practice › LeetCode › LeetCode 02xx ›

LeetCode 292 - Nim Game

LeetCode Problem 292 Difficulty: 🟢 Easy Topics: Math, Brainteaser, Game Theory Solution Problem Understanding The problem describes a two-player game involving a single heap of stones. There are n stones initially on the table, and players alternate turns removing stones. On each turn, a player may remove either 1, 2, or 3 stones. The player who removes the final stone wins the game. You always move first, and both players...

Practice › LeetCode › LeetCode 10xx ›

LeetCode 1033 - Moving Stones Until Consecutive

LeetCode Problem 1033 Difficulty: 🟡 Medium Topics: Math, Brainteaser Solution Problem Understanding The problem presents three stones placed on distinct positions along a one-dimensional X-axis, represented by integers a , b , and c . A move consists of taking a stone from one of the endpoints (the leftmost or rightmost stone) and placing it at an unoccupied position strictly between the endpoints. The goal is to determine two numbers:...

Practice › LeetCode › LeetCode 12xx ›

LeetCode 1227 - Airplane Seat Assignment Probability

LeetCode Problem 1227 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming, Brainteaser, Probability and Statistics Solution Problem Understanding This problem involves a scenario with n passengers and n seats on an airplane. Each passenger has a designated seat, but the first passenger has lost their ticket and picks a seat randomly. Every subsequent passenger will either take their own seat if it is unoccupied or select a random available seat if...

Practice › LeetCode › LeetCode 08xx ›

LeetCode 810 - Chalkboard XOR Game

LeetCode Problem 810 Difficulty: 🔴 Hard Topics: Array, Math, Bit Manipulation, Brainteaser, Game Theory Solution LeetCode 810, Chalkboard XOR Game Problem Understanding This problem describes a two player game played on an array of integers. The numbers are written on a chalkboard, and players take turns erasing exactly one number. Alice moves first, then Bob, and both players play optimally. The key rule is unusual. A player loses immediately if...

Practice › LeetCode › LeetCode (archived) › LeetCode 03xx ›

LeetCode 319: Bulb Switcher

Problem Restatement There are n bulbs in a row. All bulbs are initially off. We perform n rounds: Round Operation 1 Turn on every bulb 2 Toggle every second bulb 3 Toggle every third bulb i Toggle every i th bulb n Toggle only the n th bulb Return how many bulbs are on after all rounds. The official constraints are 0 <= n <= 10^9 . Input and Output...

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LeetCode 3828 - Final Element After Subarray Deletions

LeetCode 3674 - Minimum Operations to Equalize Array

LeetCode 3596 - Minimum Cost Path with Alternating Directions I

LeetCode 3577 - Count the Number of Computer Unlocking Permutations

LeetCode 2425 - Bitwise XOR of All Pairings

LeetCode 1908 - Game of Nim

LeetCode 2419 - Longest Subarray With Maximum Bitwise AND

LeetCode 2745 - Construct the Longest New String

LeetCode 2749 - Minimum Operations to Make the Integer Zero

LeetCode 2505 - Bitwise OR of All Subsequence Sums

LeetCode 3227 - Vowels Game in a String

LeetCode 2731 - Movement of Robots

LeetCode 2396 - Strictly Palindromic Number

LeetCode 2568 - Minimum Impossible OR

LeetCode 319 - Bulb Switcher

LeetCode 1503 - Last Moment Before All Ants Fall Out of a Plank

LeetCode 1025 - Divisor Game

LeetCode 292 - Nim Game

LeetCode 1033 - Moving Stones Until Consecutive

LeetCode 1227 - Airplane Seat Assignment Probability

LeetCode 810 - Chalkboard XOR Game

LeetCode 319: Bulb Switcher