LeetCode 38xx

LeetCode problems 3800–3899

76 items

LeetCode 38xx

# Problem Difficulty Time Notes
3801 Minimum Cost to Merge Sorted Lists 🔴 Hard 1m 34s We are given between 2 and 12 sorted lists. At any moment we may ch…
3802 Number of Ways to Paint Sheets 🔴 Hard 43s The problem asks us to compute the number of ways to paint n sheets…
3803 Count Residue Prefixes 🟢 Easy 19m 49s The problem asks us to analyze prefixes of a string s and count how…
3804 Number of Centered Subarrays 🟡 Medium 50s The problem asks us to count the number of centered subarrays in a …
3805 Count Caesar Cipher Pairs 🟡 Medium 1m 39s We are given an array words containing n lowercase strings. Every s…
3806 Maximum Bitwise AND After Increment Operations 🔴 Hard 1m 14s The problem asks us to find the maximum possible bitwise AND of any…
3807 Minimum Cost to Repair Edges to Traverse a Graph 🟡 Medium 54s The problem presents an undirected graph with n nodes labeled from …
3808 Find Emotionally Consistent Users 🟡 Medium 1m 30s This problem asks us to analyze user reactions and determine which …
3811 Number of Alternating XOR Partitions 🟡 Medium 2m 6s We are given an array nums and two distinct target XOR values, targ…
3812 Minimum Edge Toggles on a Tree 🔴 Hard 1m 58s We are given a tree with n nodes and n - 1 edges. Every node has a …
3813 Vowel-Consonant Score 🟢 Easy 1m 34s The problem asks us to compute a score for a given string s. The st…
3815 Design Auction System 🟡 Medium 1m 47s This problem asks us to design a real time auction system that supp…
3816 Lexicographically Smallest String After Deleting Duplicate Characters 🔴 Hard 1m 31s We are given a string s consisting only of lowercase English letter…
3817 Good Indices in a Digit String 🟡 Medium 1m 37s We are given a string s consisting only of decimal digits. The stri…
3818 Minimum Prefix Removal to Make Array Strictly Increasing 🟡 Medium 46s The problem asks us to process an integer array nums and determine …
3819 Rotate Non Negative Elements 🟡 Medium 47s The problem asks us to rotate only the non-negative elements of an …
3821 Find Nth Smallest Integer With K One Bits 🔴 Hard 37s This problem asks us to find the nth smallest positive integer whos…
3822 Design Order Management System 🟡 Medium 1m 42s This problem asks us to implement a small in-memory order managemen…
3823 Reverse Letters Then Special Characters in a String 🟢 Easy 1m 32s This problem gives us a string s that contains two types of charact…
3825 Longest Strictly Increasing Subsequence With Non-Zero Bitwise AND 🟡 Medium 47s This problem asks us to find the longest strictly increasing subseq…
3826 Minimum Partition Score 🔴 Hard 2m 10s We are given an array nums and must divide it into exactly k contig…
3827 Count Monobit Integers 🟢 Easy 47s The problem asks us to count Monobit integers from 0 to n. A Monobi…
3828 Final Element After Subarray Deletions 🟡 Medium 3m 38s We are given an integer array nums. Two players, Alice and Bob, rep…
3829 Design Ride Sharing System 🟡 Medium 4m 5s The problem asks us to design a ride sharing system that manages bo…
3830 Longest Alternating Subarray After Removing At Most One Element 🔴 Hard 2m 26s The problem asks us to find the longest alternating subarray in a g…
3832 Find Users with Persistent Behavior Patterns 🔴 Hard 1m 14s The activity table records user actions. Each row contains a userid…
3833 Count Dominant Indices 🟢 Easy 1m 30s The problem gives us an integer array nums of length n. For every i…
3834 Merge Adjacent Equal Elements 🟡 Medium 2m 19s The problem asks us to repeatedly merge adjacent equal elements in …
3835 Count Subarrays With Cost Less Than or Equal to K 🟡 Medium 2m 19s We are given an array nums and an integer k. For every subarray num…
3836 Maximum Score Using Exactly K Pairs 🔴 Hard 2m 20s We are given two arrays, nums1 of length n and nums2 of length m, a…
3837 Delayed Count of Equal Elements 🟡 Medium 46s The problem requires computing a delayed count for each element in …
3838 Weighted Word Mapping 🟢 Easy 1m 33s The problem provides two inputs: - words, an array of lowercase Eng…
3839 Number of Prefix Connected Groups 🟡 Medium 1m 29s The problem gives us an array of strings words and an integer k. Tw…
3840 House Robber V 🟡 Medium 52s The problem is a variation of the classic House Robber problem, but…
3841 Palindromic Path Queries in a Tree 🔴 Hard 1m 32s We are given a tree with n nodes. Each node stores a lowercase Engl…
3842 Toggle Light Bulbs 🟢 Easy 1m 26s The problem gives us an array bulbs, where each value represents a …
3844 Longest Almost-Palindromic Substring 🟡 Medium 2m 6s We are given a string s consisting of lowercase English letters. We…
3845 Maximum Subarray XOR with Bounded Range 🔴 Hard 40s The problem asks us to find a subarray of a given non-negative inte…
3846 Total Distance to Type a String Using One Finger 🟡 Medium 1m 27s This problem asks us to calculate the total finger movement require…
3847 Find the Score Difference in a Game 🟡 Medium 1m 4s This problem describes a game played over a sequence of rounds. The…
3848 Check Digitorial Permutation 🟡 Medium 43s The problem asks us to determine whether any permutation of the dig…
3850 Count Sequences to K 🔴 Hard 2m We start with a value val = 1 and process the array from left to ri…
3851 Maximum Requests Without Violating the Limit 🟡 Medium 1m 25s We are given a list of requests, where each request consists of a u…
3852 Smallest Pair With Different Frequencies 🟢 Easy 1m 29s This problem gives us an integer array nums and asks us to find a p…
3853 Merge Close Characters 🟡 Medium 55s The problem asks us to repeatedly merge close, equal characters in …
3854 Minimum Operations to Make Array Parity Alternating 🟡 Medium 2m 18s We are given an integer array nums. An array is called parity alter…
3855 Sum of K-Digit Numbers in a Range 🔴 Hard 1m 12s We are given three integers l, r, and k. For every digit position, …
3856 Trim Trailing Vowels 🟢 Easy 1m 24s This problem asks us to remove all vowels that appear at the end of…
3857 Minimum Cost to Split into Ones 🟡 Medium 1m 14s We are given a single integer n. Starting with this integer, we rep…
3858 Minimum Bitwise OR From Grid 🟡 Medium 1m 52s We are given an m x n grid of positive integers. From each row, we …
3860 Unique Email Groups 🟡 Medium 1m 17s This problem asks us to determine how many distinct email groups ex…
3862 Find the Smallest Balanced Index 🟡 Medium 1m 33s We are given an integer array nums, and we need to find the smalles…
3863 Minimum Operations to Sort a String 🟡 Medium 57s This problem is asking us to determine the minimum number of substr…
3864 Minimum Cost to Partition a Binary String 🔴 Hard 1m 26s We are given a binary string s, where each character represents whe…
3865 Reverse K Subarrays 🟡 Medium 57s The problem asks us to take an integer array nums of length n and d…
3866 First Unique Even Element 🟢 Easy 56s The problem asks us to find the first even integer in an array that…
3867 Sum of GCD of Formed Pairs 🟡 Medium 1m 28s We are given an integer array nums of length n. For every index i, …
3868 Minimum Cost to Equalize Arrays Using Swaps 🟡 Medium 55s The problem requires us to make two integer arrays nums1 and nums2 …
3869 Count Fancy Numbers in a Range 🔴 Hard 2m 40s We are given two integers l and r, and we must count how many integ…
3870 Count Commas in Range 🟢 Easy 1m 15s The problem asks us to count how many commas appear when writing ev…
3871 Count Commas in Range II 🟡 Medium 1m 3s The problem asks us to count the total number of commas that appear…
3872 Longest Arithmetic Sequence After Changing At Most One Element 🟡 Medium 43s The problem requires us to find the longest arithmetic subarray fro…
3873 Maximum Points Activated with One Addition 🔴 Hard 44s The problem is asking us to simulate a chain reaction of activation…
3875 Construct Uniform Parity Array I 🟢 Easy 39s The problem asks us to determine if it is possible to construct a n…
3876 Construct Uniform Parity Array II 🟡 Medium 51s The problem asks us to determine whether we can construct a new arr…
3877 Minimum Removals to Achieve Target XOR 🟡 Medium 2m 3s We are given an array nums and a target value target. We may remove…
3878 Count Good Subarrays 🔴 Hard 2m 39s We are given an integer array nums, and we must count how many suba…
3879 Maximum Distinct Path Sum in a Binary Tree 🟡 Medium 47s The problem asks us to find the maximum sum of node values along a …
3880 Minimum Absolute Difference Between Two Values 🟢 Easy 1m 37s The problem gives us an integer array nums where every element is g…
3881 Direction Assignments with Exactly K Visible People 🟡 Medium 1m 11s We are given n people standing in a line, indexed from 0 to n - 1. …
3882 Minimum XOR Path in a Grid 🟡 Medium 1m 33s We are given an m × n grid of integers. Starting from the top-left …
3883 Count Non Decreasing Arrays With Given Digit Sums 🔴 Hard 39s The problem asks us to compute the number of non-decreasing arrays …
3884 First Matching Character From Both Ends 🟢 Easy 1m 23s This problem gives us a string s of length n consisting of lowercas…
3885 Design Event Manager 🟡 Medium 1m 10s The problem asks us to design an EventManager class that manages a …
3889 Mirror Frequency Distance 🟡 Medium 1m 12s We are given a string s containing only lowercase English letters (…
3890 Integers With Multiple Sum of Two Cubes 🟡 Medium 55s The problem asks us to find all integers x less than or equal to a …
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LeetCode 3801 - Minimum Cost to Merge Sorted Lists

We are given between 2 and 12 sorted lists. At any moment we may choose any two existing lists and merge them. If the two lists are and , the merge cost is After the merge, the two lists disappear and are replaced by their sorted union.
leetcode Hard array two-pointers binary-search dynamic-programming bit-manipulation May 30, 2026
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LeetCode 3802 - Number of Ways to Paint Sheets

The problem asks us to compute the number of ways to paint n sheets using exactly two distinct colors, subject to constraints on the maximum number of sheets each color can paint.
leetcode Hard May 30, 2026
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LeetCode 3803 - Count Residue Prefixes

The problem asks us to analyze prefixes of a string s and count how many of them satisfy a specific condition. A prefix is any substring that starts at the first character and extends to some point in the string.
leetcode Easy hash-table string May 30, 2026
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LeetCode 3804 - Number of Centered Subarrays

The problem asks us to count the number of centered subarrays in a given integer array nums. A subarray is called centered if the sum of its elements is equal to at least one element within that subarray.
leetcode Medium array hash-table enumeration May 30, 2026
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LeetCode 3805 - Count Caesar Cipher Pairs

We are given an array words containing n lowercase strings. Every string has the same length m. Two strings are considered similar if we can repeatedly apply the following operation to either string: - Shift every character forward by one position in the alphabet.
leetcode Medium array hash-table math string counting May 30, 2026
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LeetCode 3806 - Maximum Bitwise AND After Increment Operations

The problem asks us to find the maximum possible bitwise AND of any subset of size m from an array nums after performing up to k increment operations. Each operation allows us to increase any element in the array by 1.
leetcode Hard array greedy bit-manipulation sorting May 30, 2026
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LeetCode 3807 - Minimum Cost to Repair Edges to Traverse a Graph

The problem presents an undirected graph with n nodes labeled from 0 to n-1 and m edges. Each edge has a repair cost, and initially, all edges are damaged. We can spend a certain amount of money to repair all edges whose cost is less than or equal to that amount.
leetcode Medium binary-search breadth-first-search graph-theory May 30, 2026
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LeetCode 3808 - Find Emotionally Consistent Users

This problem asks us to analyze user reactions and determine which users exhibit a strong preference for a particular reaction type. The input is a table named reactions, where each row represents a reaction given by a user to a specific content item.
leetcode Medium May 30, 2026
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LeetCode 3811 - Number of Alternating XOR Partitions

We are given an array nums and two distinct target XOR values, target1 and target2. A partition divides the array into contiguous, non-empty blocks. Every element must belong to exactly one block, and the blocks must cover the entire array.
leetcode Medium array hash-table dynamic-programming bit-manipulation May 30, 2026
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LeetCode 3812 - Minimum Edge Toggles on a Tree

We are given a tree with n nodes and n - 1 edges. Every node has a binary color represented by the strings start and target. An operation consists of selecting an edge and toggling both of its endpoints.
leetcode Hard tree depth-first-search graph-theory topological-sort sorting May 30, 2026
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LeetCode 3813 - Vowel-Consonant Score

The problem asks us to compute a score for a given string s. The string may contain lowercase English letters, spaces, and digits. We need to count two quantities: - v, the number of vowels in the string. - c, the number of consonants in the string.
leetcode Easy string simulation May 30, 2026
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LeetCode 3815 - Design Auction System

This problem asks us to design a real time auction system that supports inserting, updating, removing, and querying bids efficiently. Each bid is uniquely identified by the pair (userId, itemId). A user may have at most one active bid for a particular item.
leetcode Medium hash-table design heap-(priority-queue) ordered-set May 30, 2026
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LeetCode 3816 - Lexicographically Smallest String After Deleting Duplicate Characters

We are given a string s consisting only of lowercase English letters. The allowed operation is very specific: if a character currently appears at least twice in the string, we may delete exactly one occurrence of that character.
leetcode Hard hash-table string stack greedy monotonic-stack May 30, 2026
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LeetCode 3817 - Good Indices in a Digit String

We are given a string s consisting only of decimal digits. The string length is n, and indices are zero-based. For every index i, we need to determine whether i is a good index.
leetcode Medium math string May 30, 2026
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LeetCode 3818 - Minimum Prefix Removal to Make Array Strictly Increasing

The problem asks us to process an integer array nums and determine the minimum length of a prefix that we can remove so that the remaining array becomes strictly increasing.
leetcode Medium array May 30, 2026
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LeetCode 3819 - Rotate Non Negative Elements

The problem asks us to rotate only the non-negative elements of an integer array nums to the left by k positions in a cyclic manner, while leaving all negative elements fixed in their original positions.
leetcode Medium array simulation May 30, 2026
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LeetCode 3821 - Find Nth Smallest Integer With K One Bits

This problem asks us to find the nth smallest positive integer whose binary representation contains exactly k ones. In other words, we are working with numbers that, when written in binary, have a specific number of bits set to 1.
leetcode Hard math bit-manipulation combinatorics May 30, 2026
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LeetCode 3822 - Design Order Management System

This problem asks us to implement a small in-memory order management system that supports four operations on trading orders.
leetcode Medium hash-table design May 30, 2026
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LeetCode 3823 - Reverse Letters Then Special Characters in a String

This problem gives us a string s that contains two types of characters: 1. Lowercase English letters ('a' to 'z') 2. Special characters from the set "!@$%^&()" We must perform two independent reversals, in a specific order.
leetcode Easy two-pointers string simulation May 30, 2026
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LeetCode 3825 - Longest Strictly Increasing Subsequence With Non-Zero Bitwise AND

This problem asks us to find the longest strictly increasing subsequence (LIS) in a given integer array nums, with the additional constraint that the bitwise AND of all elements in the subsequence must be non-zero.
leetcode Medium array binary-search bit-manipulation enumeration May 30, 2026
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LeetCode 3826 - Minimum Partition Score

We are given an array nums and must divide it into exactly k contiguous subarrays. For every subarray, we first compute its sum: Its value is then defined as: The score of a partition is the sum of the values of all subarrays in that partition.
leetcode Hard array divide-and-conquer dynamic-programming queue prefix-sum monotonic-queue May 30, 2026
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LeetCode 3827 - Count Monobit Integers

The problem asks us to count Monobit integers from 0 to n. A Monobit integer is one where all bits in its binary representation are the same. This means there are only two possibilities for a valid Monobit integer: all zeros or all ones.
leetcode Easy bit-manipulation enumeration May 30, 2026
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LeetCode 3828 - Final Element After Subarray Deletions

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.
leetcode Medium array math brainteaser game-theory May 30, 2026
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LeetCode 3829 - Design Ride Sharing System

The problem asks us to design a ride sharing system that manages both riders and drivers as they enter the system, and to match them in a first-come, first-served order.
leetcode Medium hash-table design queue data-stream May 30, 2026
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LeetCode 3830 - Longest Alternating Subarray After Removing At Most One Element

The problem asks us to find the longest alternating subarray in a given integer array nums, where a subarray is defined as consecutive elements.
leetcode Hard array dynamic-programming enumeration May 30, 2026
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LeetCode 3832 - Find Users with Persistent Behavior Patterns

The activity table records user actions. Each row contains a userid, the actiondate, and the specific action performed on that date. The primary key is (userid, actiondate, action), which guarantees that the exact same action for the same user on the same day cannot appear twice.
leetcode Hard May 30, 2026
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LeetCode 3833 - Count Dominant Indices

The problem gives us an integer array nums of length n. For every index i, we must determine whether the element nums[i] is dominant. An index is considered dominant if its value is strictly greater than the average of all elements to its right.
leetcode Easy array enumeration May 30, 2026
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LeetCode 3834 - Merge Adjacent Equal Elements

The problem asks us to repeatedly merge adjacent equal elements in an integer array nums until no further merges are possible. Specifically, if two consecutive elements are equal, we replace them with their sum.
leetcode Medium array stack simulation May 30, 2026
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LeetCode 3835 - Count Subarrays With Cost Less Than or Equal to K

We are given an array nums and an integer k. For every subarray nums[l..r], its cost is defined as: The first part measures the range of values inside the subarray, while the second part measures the length of the subarray.
leetcode Medium array queue monotonic-queue May 30, 2026
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LeetCode 3836 - Maximum Score Using Exactly K Pairs

We are given two arrays, nums1 of length n and nums2 of length m, along with an integer k. Our goal is to choose exactly k pairs of indices: such that: and For every chosen pair (i, j), we gain a score equal to: The final score is the sum of the products of all selected pairs…
leetcode Hard array dynamic-programming May 30, 2026
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LeetCode 3837 - Delayed Count of Equal Elements

The problem requires computing a delayed count for each element in an array nums. For an index i, the delayed count is defined as the number of later elements (indices j i + k) that are equal to nums[i].
leetcode Medium array hash-table counting May 30, 2026
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LeetCode 3838 - Weighted Word Mapping

The problem provides two inputs: - words, an array of lowercase English strings. - weights, an array of 26 integers where weights[i] represents the weight assigned to the letter corresponding to index i (0 - 'a', 1 - 'b', ..., 25 - 'z').
leetcode Easy array string simulation May 30, 2026
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LeetCode 3839 - Number of Prefix Connected Groups

The problem gives us an array of strings words and an integer k. Two words are considered prefix-connected if they share exactly the same first k characters and they come from different indices in the array.
leetcode Medium array hash-table string counting May 30, 2026
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LeetCode 3840 - House Robber V

The problem is a variation of the classic House Robber problem, but with an additional constraint: each house has a color, and you cannot rob two adjacent houses if they share the same color. We are given two arrays nums and colors of length n.
leetcode Medium array dynamic-programming May 30, 2026
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LeetCode 3841 - Palindromic Path Queries in a Tree

We are given a tree with n nodes. Each node stores a lowercase English letter. The tree is undirected and connected, so there is exactly one simple path between any two nodes. The problem supports two kinds of operations: 1. Update Change the character assigned to a node. 2.
leetcode Hard array string divide-and-conquer tree segment-tree May 30, 2026
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LeetCode 3842 - Toggle Light Bulbs

The problem gives us an array bulbs, where each value represents a light bulb number between 1 and 100. Initially, there are exactly 100 light bulbs, and every bulb is turned off. We process the array from left to right.
leetcode Easy array hash-table sorting simulation May 30, 2026
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LeetCode 3844 - Longest Almost-Palindromic Substring

We are given a string s consisting of lowercase English letters. We must find the length of the longest substring that is almost-palindromic.
leetcode Medium two-pointers string dynamic-programming May 30, 2026
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LeetCode 3845 - Maximum Subarray XOR with Bounded Range

The problem asks us to find a subarray of a given non-negative integer array nums such that the difference between the maximum and minimum elements of the subarray does not exceed a given integer k.
leetcode Hard array bit-manipulation trie queue sliding-window prefix-sum monotonic-queue May 30, 2026
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LeetCode 3846 - Total Distance to Type a String Using One Finger

This problem asks us to calculate the total finger movement required to type a given lowercase string on a special keyboard layout using only one finger. The keyboard is arranged as: Each key occupies a coordinate (row, column) in this grid.
leetcode Medium hash-table string May 30, 2026
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LeetCode 3847 - Find the Score Difference in a Game

This problem describes a game played over a sequence of rounds. The array nums represents the points awarded in each game, where nums[i] is the number of points available during game i. There are exactly two players. At the beginning: - The first player is active.
leetcode Medium array simulation May 30, 2026
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LeetCode 3848 - Check Digitorial Permutation

The problem asks us to determine whether any permutation of the digits of a given integer n forms a digitorial number. A digitorial number is defined as a number equal to the sum of the factorials of its digits. For instance, 145 is digitorial because .
leetcode Medium math counting May 30, 2026
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LeetCode 3850 - Count Sequences to K

We start with a value val = 1 and process the array from left to right. For every element nums[i], we must choose exactly one of three actions: - Multiply the current value by nums[i] - Divide the current value by nums[i] - Do nothing Division is exact rational division, not…
leetcode Hard array math dynamic-programming memoization number-theory May 30, 2026
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LeetCode 3851 - Maximum Requests Without Violating the Limit

We are given a list of requests, where each request consists of a user ID and a timestamp. Multiple users can appear in the input, and a user may have multiple requests at different times.
leetcode Medium array hash-table greedy sliding-window sorting May 30, 2026
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LeetCode 3852 - Smallest Pair With Different Frequencies

This problem gives us an integer array nums and asks us to find a pair of distinct values [x, y] that satisfies two conditions: 1. x < y 2. The frequency of x in the array is different from the frequency of y.
leetcode Easy array hash-table counting May 30, 2026
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LeetCode 3853 - Merge Close Characters

The problem asks us to repeatedly merge close, equal characters in a string s. A character pair is considered close if the distance between their indices is at most k. When a merge occurs, the right character is removed and the string is updated immediately.
leetcode Medium hash-table string May 30, 2026
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LeetCode 3854 - Minimum Operations to Make Array Parity Alternating

We are given an integer array nums. An array is called parity alternating when every pair of adjacent elements has different parity. In other words, the parity pattern must alternate between even and odd.
leetcode Medium array greedy May 30, 2026
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LeetCode 3855 - Sum of K-Digit Numbers in a Range

We are given three integers l, r, and k. For every digit position, we may independently choose any digit from the inclusive range [l, r]. We then form all possible numbers consisting of exactly k digits.
leetcode Hard math divide-and-conquer combinatorics number-theory May 30, 2026
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LeetCode 3856 - Trim Trailing Vowels

This problem asks us to remove all vowels that appear at the end of a given string. The input is a string s consisting only of lowercase English letters. A vowel is defined as one of the five characters: 'a', 'e', 'i', 'o', or 'u'.
leetcode Easy string May 30, 2026
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LeetCode 3857 - Minimum Cost to Split into Ones

We are given a single integer n. Starting with this integer, we repeatedly perform split operations until every resulting piece is equal to 1.
leetcode Medium math dynamic-programming May 30, 2026
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LeetCode 3858 - Minimum Bitwise OR From Grid

We are given an m x n grid of positive integers. From each row, we must choose exactly one value. After making one choice per row, we compute the bitwise OR of all selected values. Our goal is to make that final OR value as small as possible.
leetcode Medium array greedy bit-manipulation matrix May 30, 2026
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LeetCode 3860 - Unique Email Groups

This problem asks us to determine how many distinct email groups exist after applying a specific normalization process to every email address. Each email consists of two parts separated by the '@' character: - The local name appears before '@'.
leetcode Medium array hash-table string May 30, 2026
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LeetCode 3862 - Find the Smallest Balanced Index

We are given an integer array nums, and we need to find the smallest index i that satisfies a special balance condition. For a given index i: - The left sum is the sum of all elements strictly before i, that is, nums[0] + nums[1] + ... + nums[i-1].
leetcode Medium array prefix-sum May 30, 2026
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LeetCode 3863 - Minimum Operations to Sort a String

This problem is asking us to determine the minimum number of substring sort operations needed to make a string s sorted in non-descending alphabetical order. We are allowed to sort any substring of s, but we cannot sort the entire string at once.
leetcode Medium string May 30, 2026
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LeetCode 3864 - Minimum Cost to Partition a Binary String

We are given a binary string s, where each character represents whether an element is sensitive: - '1' means the element is sensitive. - '0' means the element is not sensitive. The entire string initially forms one segment.
leetcode Hard string divide-and-conquer prefix-sum May 30, 2026
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LeetCode 3865 - Reverse K Subarrays

The problem asks us to take an integer array nums of length n and divide it into k contiguous subarrays of equal length, then reverse each subarray individually. The resulting array should preserve the order of the subarrays but reflect the reversal within each one.
leetcode Medium array two-pointers May 30, 2026
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LeetCode 3866 - First Unique Even Element

The problem asks us to find the first even integer in an array that appears exactly once. In other words, we need to traverse the array and identify even numbers, count their occurrences, and return the earliest one that occurs only a single time.
leetcode Easy array hash-table counting May 30, 2026
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LeetCode 3867 - Sum of GCD of Formed Pairs

We are given an integer array nums of length n. For every index i, we first compute: - mxi, the maximum value among nums[0...i] - prefixGcd[i] = gcd(nums[i], mxi) This creates a new array called prefixGcd. After that, we sort prefixGcd in non-decreasing order.
leetcode Medium array math two-pointers simulation number-theory May 30, 2026
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LeetCode 3868 - Minimum Cost to Equalize Arrays Using Swaps

The problem requires us to make two integer arrays nums1 and nums2 identical by performing swaps. There are two types of swaps: swaps within the same array, which are free, and swaps between arrays at the same index, which cost 1 per operation.
leetcode Medium array hash-table greedy counting May 30, 2026
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LeetCode 3869 - Count Fancy Numbers in a Range

We are given two integers l and r, and we must count how many integers in the inclusive range [l, r] are fancy. The definition of a fancy number is based on the concept of a good number. A number is good if its digits form a strictly monotone sequence.
leetcode Hard math dynamic-programming May 30, 2026
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LeetCode 3870 - Count Commas in Range

The problem asks us to count how many commas appear when writing every integer from 1 through n using standard number formatting. In standard formatting, commas are inserted every three digits from the right side of the number. For example: - 999 contains 0 commas.
leetcode Easy math May 30, 2026
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LeetCode 3871 - Count Commas in Range II

The problem asks us to count the total number of commas that appear when writing every integer from 1 through n using standard comma-separated number formatting. In standard formatting, commas are inserted every three digits from the right: - 1 through 999 contain no commas.
leetcode Medium math May 30, 2026
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LeetCode 3872 - Longest Arithmetic Sequence After Changing At Most One Element

The problem requires us to find the longest arithmetic subarray from a given array of integers nums if we are allowed to modify at most one element. An arithmetic subarray is a contiguous sequence in which the difference between consecutive elements is constant.
leetcode Medium array enumeration May 30, 2026
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LeetCode 3873 - Maximum Points Activated with One Addition

The problem is asking us to simulate a chain reaction of activations on a set of 2D points. Each point is defined by its (x, y) coordinates and all points are distinct. When a point is activated, any point sharing the same x coordinate or y coordinate becomes activated as well.
leetcode Hard array hash-table union-find May 30, 2026
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LeetCode 3875 - Construct Uniform Parity Array I

The problem asks us to determine if it is possible to construct a new array nums2 of the same length as nums1 where all elements are either all odd or all even.
leetcode Easy array math May 30, 2026
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LeetCode 3876 - Construct Uniform Parity Array II

The problem asks us to determine whether we can construct a new array nums2 from a given array nums1 of distinct integers such that all elements in nums2 have the same parity (all even or all odd).
leetcode Medium array math May 30, 2026
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LeetCode 3877 - Minimum Removals to Achieve Target XOR

We are given an array nums and a target value target. We may remove any subset of elements from the array, including removing none of them or even removing all of them. After performing the removals, the remaining elements form a new array.
leetcode Medium array dynamic-programming bit-manipulation May 30, 2026
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LeetCode 3878 - Count Good Subarrays

We are given an integer array nums, and we must count how many subarrays are good. A subarray is considered good if the bitwise OR of all elements in that subarray is equal to at least one element that appears inside the same subarray.
leetcode Hard array stack bit-manipulation monotonic-stack May 30, 2026
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LeetCode 3879 - Maximum Distinct Path Sum in a Binary Tree

The problem asks us to find the maximum sum of node values along a path in a binary tree such that all values in the path are distinct. The path can start and end at any node, does not need to pass through the root, and must consist of connected nodes.
leetcode Medium hash-table tree depth-first-search binary-tree May 30, 2026
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LeetCode 3880 - Minimum Absolute Difference Between Two Values

The problem gives us an integer array nums where every element is guaranteed to be one of three values: 0, 1, or 2.
leetcode Easy array enumeration May 30, 2026
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LeetCode 3881 - Direction Assignments with Exactly K Visible People

We are given n people standing in a line, indexed from 0 to n - 1. Each person independently chooses one of two directions: - 'L' means the person is visible only to people on their right. - 'R' means the person is visible only to people on their left.
leetcode Medium math combinatorics May 30, 2026
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LeetCode 3882 - Minimum XOR Path in a Grid

We are given an m × n grid of integers. Starting from the top-left cell (0, 0), we must reach the bottom-right cell (m - 1, n - 1) by moving only right or down.
leetcode Medium array dynamic-programming bit-manipulation matrix May 30, 2026
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LeetCode 3883 - Count Non Decreasing Arrays With Given Digit Sums

The problem asks us to compute the number of non-decreasing arrays of integers where each integer satisfies a specific digit sum constraint.
leetcode Hard array dynamic-programming prefix-sum May 30, 2026
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LeetCode 3884 - First Matching Character From Both Ends

This problem gives us a string s of length n consisting of lowercase English letters. For every index i, we compare two characters: - The character at position i, which is s[i] - The character at the mirrored position from the other end, which is s[n - i - 1] We must find the…
leetcode Easy two-pointers string May 30, 2026
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LeetCode 3885 - Design Event Manager

The problem asks us to design an EventManager class that manages a set of events, each identified by a unique eventId and associated with a priority.
leetcode Medium array hash-table design heap-(priority-queue) ordered-set May 30, 2026
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LeetCode 3889 - Mirror Frequency Distance

We are given a string s containing only lowercase English letters (a-z) and digits (0-9). Each character has a corresponding mirror character: - Letters are mirrored across the alphabet. - a ↔ z - b ↔ y - c ↔ x - and so on. - Digits are mirrored across the digit range.
leetcode Medium hash-table string counting May 30, 2026
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LeetCode 3890 - Integers With Multiple Sum of Two Cubes

The problem asks us to find all integers x less than or equal to a given integer n such that x can be expressed as the sum of cubes of two positive integers in at least two distinct ways.
leetcode Medium hash-table sorting counting enumeration May 30, 2026