Simulation pattern

optimized simulation based on sum difference constraint using the sum of differences between left and right elements to prune search space array manipulation and counting

Full post LeetCode Kotlin Rust YouTube Telegram

25.10.2025

easy

1716. Calculate Money in Leetcode Bank

Kotlin Rust

Add increasing sum of money, drop weekly gain on mondays

Simulation

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23.10.2025

easy

3461. Check If Digits Are Equal in String After Operations I

Kotlin Rust

Fold each pair to (a+b)%10 until 2 left

Simulation String

arrays dynamic programming pascal triangle generation mathematics

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20.10.2025

easy

2011. Final Value of Variable After Performing Operations

Kotlin Rust

do ++ or -- operation from 0

Simulation

string_operations

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13.10.2025

medium

2273. Find Resultant Array After Removing Anagrams

Kotlin Rust

Dedup anagrams

Simulation String Array

array hash map sorting grouping frequency map strings

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02.10.2025

medium

3100. Water Bottles II

Kotlin Rust

Total drinks with growing exchange rate empty for full

Simulation

simulation of a process with state tracking finding an O(1) mathematical solution mathematical calculation

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01.10.2025

easy

1518. Water Bottles

Kotlin Rust

Total drinks with exchange empty for full

Simulation

deriving formula from geometric series convergence to calculate total drinks using geometric series to find the sum of an infinite series

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30.09.2025

medium

2221. Find Triangular Sum of an Array

Kotlin Rust

Triangle sum % 10

Simulation Array

n fold simulation zipWithNext binomial_coefficient_relation arrays

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16.09.2025

hard

2197. Replace Non-Coprime Numbers in Array

Kotlin Rust

Simulate gcd to lcm adjacent pair removal

Simulation Math Array

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10.09.2025

medium

1733. Minimum Number of People to Teach

Kotlin

Min friends to teach common language to communicate in graph

Graph Simulation

set array none set_difference set_intersection graph

Full post LeetCode Kotlin YouTube Telegram

09.09.2025

medium

2327. Number of People Aware of a Secret

Kotlin

People knowing a secret at day n, keeping delay then spread and forget

Simulation Dynamic Programming Array

array dynamic_programming prefix_sum simulation

Full post LeetCode Kotlin YouTube Telegram

08.09.2025

easy

1317. Convert Integer to the Sum of Two No-Zero Integers

Kotlin Rust

Find a+b=n without zeros in digits

Simulation

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10.08.2025

medium

869. Reordered Power of 2

Kotlin Rust

Rearrange digits to make power of two

Graph Bit Manipulation Simulation

groupBy frequency array depth-first search sorting two-pointers frequency comparison

Full post LeetCode Kotlin Rust YouTube Telegram

5.08.2025

easy

3477. Fruits Into Baskets II

Kotlin Rust

Place fruits left to right to first available bucket

Simulation

f s brute-force segment_tree segment_tree_max f

Full post LeetCode Kotlin Rust YouTube Telegram

2.08.2025

hard

2561. Rearranging Fruits

Kotlin

Min swaps cost to make a==b

Greedy Simulation

hash-map tree greedy grouping two-pointers arrays

Full post LeetCode Kotlin YouTube Telegram

12.07.2025

hard

1900. The Earliest and Latest Rounds Where Players Compete

Kotlin

First and last round Alice fight Bob

Simulation

bitmask depth-first-search backtracking simulation state-space-search combinatorics

Full post LeetCode Kotlin YouTube Telegram

11.07.2025

hard

2402. Meeting Rooms III

Kotlin Rust

Most frequent meeting room

Heap Simulation

heap array array sorting greedy linear-scan

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3.07.2025

easy

3304. Find the K-th Character in String Game I

Kotlin Rust

kth char after appending rotated self

Simulation String

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24.06.2025

easy

2200. Find All K-Distant Indices in an Array

Kotlin Rust

Indices k-distant to key

Simulation Array

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21.06.2025

medium

3085. Minimum Deletions to Make String K-Special

Kotlin Rust

Min remove to make frequencies k-narrow

Simulation String

frequency_counting_array frequency_array brute_force_optimization prefix_sum_intuition frequency_counting brute_force_optimization

Full post LeetCode Kotlin Rust YouTube Telegram

15.06.2025

medium

1432. Max Difference You Can Get From Changing an Integer

Kotlin Rust

Max - min, replacing any digit, no leading zeros

Simulation

Brute force enumeration of all possible numbers by changing digits to other digits. Iterating through all combinations of replacing each digit with any digit from 0 to 9. Manipulating the string representation of the integer. Implicitly dealing with the digits as an array/sequence.

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06.06.2025

medium

2434. Using a Robot to Print the Lexicographically Smallest String

Kotlin Rust

Smallest string by writing to stack

String Stack Simulation

stack array list greedy monotonic-stack strings

Full post LeetCode Kotlin Rust YouTube Telegram

03.06.2025

hard

1298. Maximum Candies You Can Get from Boxes

Kotlin Rust

Open boxes graph with keys simulation

Graph Simulation

LinkedList Queue Breadth-First Search Cycle Handling State Marking Graph

Full post LeetCode Kotlin Rust YouTube Telegram

13.05.2025

medium

3335. Total Characters in String After Transformations I

Kotlin Rust

String length after t shifts c=c+1,z=ab

Dynamic Programming Simulation String

frequency array frequency transformation simulating character growth via frequency updates handling large sums with modulo operations character transformations

Full post LeetCode Kotlin Rust YouTube Telegram

02.05.2025

medium

838. Push Dominoes

Kotlin Rust

Dominoes simulation

Simulation

string array linear-scan two-pointers linear-time-manipulation strings

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18.04.2025

medium

38. Count and Say

Kotlin Rust

nth run-length encoded string

Simulation String

array looping run-length encoding string manipulation

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17.04.2025

easy

2176. Count Equal and Divisible Pairs in an Array

Kotlin Rust

Pairs a[i] == b[j], i j % k == 0

Simulation Array

Full post LeetCode Kotlin Rust YouTube Telegram

14.04.2025

easy

1534. Count Good Triplets

Kotlin Rust

Triplets with diff less than a,b,c

Simulation

arrays brute-force

Full post LeetCode Kotlin Rust YouTube Telegram

09.04.2025

easy

3375. Minimum Operations to Make Array Values Equal to K

Kotlin Rust

Count number bigger than k

Simulation Array

bitset counting bitset_usage arrays

Full post LeetCode Kotlin Rust YouTube Telegram

08.04.2025

easy

3396. Minimum Number of Operations to Make Elements in Array Distinct

Kotlin Rust

Count removals 3-prefixes to deduplicate

Simulation Array

nums for_loop tail_based_check iterate_from_end array_as_map i/3_operation

Full post LeetCode Kotlin Rust YouTube Telegram

27.03.2025

medium

2780. Minimum Index of a Valid Split

Kotlin Rust

Min split index to have equal majority elements

Hash Map Simulation

HashMap SortedSet BruteForce Counting FrequencyCounting MajorityElementObservation

Full post LeetCode Kotlin Rust YouTube Telegram

03.02.2025

easy

3105. Longest Strictly Increasing or Strictly Decreasing Subarray

Kotlin Rust

Longest strict monotonic subarray

Simulation

Full post LeetCode Kotlin Rust YouTube Telegram

23.01.2025

medium

1267. Count Servers that Communicate

Kotlin Rust

Connected servers by row or column

Union Find Simulation

grid coordinates row_column_frequency nested_loops initial_intuition row_column_frequency

Full post LeetCode Kotlin Rust YouTube Telegram

21.01.2025

medium

2017. Grid Game

Kotlin Rust

Maximum of minimized paths sum

Prefix Sum Simulation Array

grid prefix sum calculation minimizing the maximum path

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07.01.2025

easy

1408. String Matching in an Array

Kotlin Rust

All substrings

Simulation String Array

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18.12.2024

easy

1475. Final Prices With a Special Discount in a Shop

Kotlin Rust

Subtract next smaller value stack

Monotonic Stack Stack Simulation

monotonic_stack stack arrays strings

Full post LeetCode Kotlin Rust YouTube Telegram

16.12.2024

easy

3264. Final Array State After K Multiplication Operations I

Kotlin Rust

Mutliply k minimums

Heap Simulation Array

BinaryHeap BinaryHeap sorting greedy heap-based-selection repeated-minimum-multiplication

Full post LeetCode Kotlin Rust YouTube Telegram

10.12.2024

medium

2981. Find Longest Special Substring That Occurs Thrice I

Kotlin Rust

Max same-char 3-windows length window

Binary Search Sliding Window Simulation

array sliding-window binary-search strings

Full post LeetCode Kotlin Rust YouTube Telegram

23.11.2024

medium

1861. Rotating the Box

Kotlin Rust

Rotate matrix and simulate the fall

Simulation Array

matrix simulation sorting explicit_pointer_tracking string_splitting_and_sorting

Full post LeetCode Kotlin Rust YouTube Telegram

18.11.2024

easy

1652. Defuse the Bomb

Kotlin Rust

Next +-k window sums window

Sliding Window Simulation

sliding-window brute-force arrays

Full post LeetCode Kotlin Rust YouTube Telegram

03.11.2024

easy

796. Rotate String

Kotlin Rust

Is string rotated goal?

Simulation String Array

string matching hashing knuth-morris-pratt string manipulation string matching

Full post LeetCode Kotlin Rust YouTube Telegram

14.10.2024

medium

2530. Maximal Score After Applying K Operations

Kotlin Rust

Replace max(arr) with ceil(max/3) k times

Heap Simulation

priority_queue BinaryHeap greedy simulation priority_queue arrays

Full post LeetCode Kotlin Rust YouTube Telegram

09.09.2024

medium

2326. Spiral Matrix IV

Kotlin Rust

LinkedList to spiral 2D matrix list

Simulation Linked List Array

ListNode Array Spiral Traversal Looping Direction Change Logic Boundary Detection

Full post LeetCode Kotlin Rust YouTube Telegram

04.09.2024

medium

874. Walking Robot Simulation

Kotlin Rust

Max distance after robot moves simulation

Simulation

set HashMap simulation rotation_matrix coordinate_transformation geometry

Full post LeetCode Kotlin Rust YouTube Telegram

03.09.2024

easy

1945. Sum of Digits of String After Convert

Kotlin Rust

Sum of number chars k times

Simulation String

Full post LeetCode Kotlin Rust YouTube Telegram

15.08.2024

easy

860. Lemonade Change

Kotlin Rust

Simulate money exchange

Simulation Queue

bills process_simulation managing_change_using_minimum_bills tracking_change_for_specific_bills array_manipulation

Full post LeetCode Kotlin Rust YouTube Telegram

13.08.2024

medium

40. Combination Sum II

Kotlin Rust

Unique target sum subsequences

Backtracking Simulation

candidates result dfs sort candidates to handle duplicates and prune search space breaking early when sum exceeds target skipping identical elements in the loop to avoid duplicate combinations

Full post LeetCode Kotlin Rust YouTube Telegram

11.08.2024

hard

1568. Minimum Number of Days to Disconnect Island

Kotlin Rust

Min changes 1 to 0 to disconnect islands

Union Find Backtracking Simulation

Union-Find Hash-Map Depth-First Search Backtracking Connected Components Grid

Full post LeetCode Kotlin Rust YouTube Telegram

08.08.2024

medium

885. Spiral Matrix III

Kotlin Rust

D spiraling order

Simulation Array

matrix set spiral_walk loop_walk path_simulation layer_by_layer_traversal

Full post LeetCode Kotlin Rust YouTube Telegram

13.07.2024

hard

2751. Robot Collisions

Kotlin Rust

D dimensional robots fight

Stack Sorting Simulation

stack array sorting stack_matching sorting_by_position simulation

Full post LeetCode Kotlin Rust YouTube Telegram

11.07.2024

medium

1190. Reverse Substrings Between Each Pair of Parentheses

Kotlin Rust

Reverse string in parentheses recursively

Simulation String

LinkedList Depth-First Search Recursion Strings

Full post LeetCode Kotlin Rust YouTube Telegram

10.07.2024

easy

1598. Crawler Log Folder

Kotlin Rust

Filesystem path depth

Simulation

iterator_fold max_function iterator_fold max_function strings arrays

Full post LeetCode Kotlin Rust YouTube Telegram

9.07.2024

medium

1701. Average Waiting Time

Kotlin Rust

Average of intersecting intervals

Simulation

Full post LeetCode Kotlin Rust YouTube Telegram

8.07.2024

medium

1823. Find the Winner of the Circular Game

Kotlin Rust

Last of k-th excluded from 1..n

Simulation Math Linked List

Full post LeetCode Kotlin Rust YouTube Telegram

7.07.2024

easy

1518. Water Bottles

Kotlin Rust

Bottles drink and exchange simulation

Math Simulation

Full post LeetCode Kotlin Rust YouTube Telegram

6.07.2024

easy

2582. Pass the Pillow

Kotlin Rust

Loop position in increasing-decreasing array

Math Simulation Array

simulating the process directly to observe patterns identifying repeating patterns in the sequence of positions mathematical operations and modular arithmetic

Full post LeetCode Kotlin Rust YouTube Telegram

17.06.2024

medium

633. Sum of Square Numbers

Kotlin Rust

Is c sum of squares? search

Binary Search Simulation

none binary-search math

Full post LeetCode Kotlin Rust YouTube Telegram

27.05.2024

easy

1608. Special Array With X Elements Greater Than or Equal X

Kotlin Rust

Count of more or equal nums[i] equal itself

Sorting Simulation Array

nums sort_unstable nums

Full post LeetCode Kotlin Rust YouTube Telegram

08.04.2024

easy

1700. Number of Students Unable to Eat Lunch

Kotlin Rust

First sandwitch not eaten by any while popped from a queue

Queue Simulation

students simulation frequency_counting using_counts_array students

Full post LeetCode Kotlin Rust YouTube Telegram

03.02.2024

medium

1043. Partition Array for Maximum Sum

Kotlin Rust

Max sum of partition array into chunks size of at most k filled with max value in chunk.

Dynamic Programming Simulation Array

input_array bottom_up_dp array_partitioning

Full post LeetCode Kotlin Rust YouTube Telegram

25.01.2024

medium

1143. Longest Common Subsequence

Kotlin Rust

Longest common subsequence of two strings.

Simulation

dp string array

Full post LeetCode Kotlin Rust YouTube Telegram

18.01.2024

easy

70. Climbing Stairs

Kotlin Rust

Ways to climb n stairs by 1 or 2 steps.

Graph Hash Map Simulation

HashMap Array Dynamic Programming Iterative Dynamic Programming Arrays

Full post LeetCode Kotlin Rust YouTube Telegram

23.12.2023

easy

1496. Path Crossing

Kotlin

Is path string of 'N', 'E', 'W', 'S' crosses

Simulation String

set coordinates

Full post LeetCode Kotlin Telegram

05.11.2023

medium

1535. Find the Winner of an Array Game

Kotlin

Find maximum of the k nearest in array

Simulation Array

Full post LeetCode Kotlin Telegram

03.11.2023

medium

767. Reorganize String

Kotlin

Non-repeating consequent chars string from another string

Dynamic Programming Simulation String

heap array greedy priorityqueue_for_frequency strings arrays

Full post LeetCode Kotlin Telegram

15.10.2023

hard

1269. Number of Ways to Stay in the Same Place After Some Steps

Kotlin

Number of ways to return to 0 after moving left, right or stay steps time

Simulation

hash-map pair depth-first-search dynamic-programming memoization brute-force-search

Full post LeetCode Kotlin Telegram

13.10.2023

easy

746. Min Cost Climbing Stairs

Kotlin

Classic DP: climbing stairs

Dynamic Programming Graph Simulation

cost array (implicit dp table) two variables for space optimization bottom-up dp reducing space complexity by only storing the two previous states iterative dp approach sequence processing

Full post LeetCode Kotlin Telegram

26.09.2023

medium

316. Remove Duplicate Letters

Kotlin

Lexicographical smallest subsequence without duplicates

Graph Greedy Simulation

set map greedy stack_simulation last_occurrence_check strings

Full post LeetCode Kotlin Telegram

12.08.2023

medium

63. Unique Paths II

Kotlin

Number of right-down ways tl->br in a matrix with obstacles

Simulation Array

row dp row-based-dp grid pathfinding

Full post LeetCode Kotlin Telegram

02.08.2023

medium

46. Permutations

Kotlin

List of all numbers permutations

Graph Backtracking Simulation

bitmask backtracking dfs permutations arrays

Full post LeetCode Kotlin Telegram

22.07.2023

medium

688. Knight Probability in Chessboard

Kotlin

Probability of making k steps on a chessboard without stepping outside

Graph Queue Simulation

hash-map pair recursion memoization dynamic-programming combinatorics

Full post LeetCode Kotlin Telegram

10.05.2023

medium

59. Spiral Matrix II

Kotlin

to detect an empty cell, we can check it for == 0

Simulation Array

Array is used to represent the matrix and store results. Iterative traversal of the matrix is used to fill the spiral pattern. Simulating a robot moving in a spiral pattern to fill the matrix. Checking boundaries and visited status before moving to the next cell. The problem involves generating a spiral matrix. Using 2D arrays to represent the matrix.

Full post LeetCode Kotlin Telegram

9.05.2023

medium

54. Spiral Matrix

Kotlin

do track the borders left, top, right, bottom

Simulation Array

matrix spiral tracking borders and moving them

Full post LeetCode Kotlin Telegram

4.05.2023

medium

649. Dota2 Senate

Kotlin

Use Queue and count how many bans are from the Radiant and from the Dire.

Queue Simulation String

queue array simulation queue_simulation strings

Full post LeetCode Kotlin Telegram

24.04.2023

easy

1046. Last Stone Weight

Kotlin

use PriorityQueue with compareByDescending

Simulation

priority-queue sorting greedy arrays

Full post LeetCode Kotlin Telegram

13.04.2023

medium

946. Validate Stack Sequences

Kotlin

use one iteration and a second pointer for pop

Stack Simulation

stack simulation stack_simulation arrays

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12.04.2023

medium

71. Simplify Path

Kotlin

split the string by /

Stack Simulation String

Stack Stack Simulation Strings

Full post LeetCode Kotlin Telegram

07.03.2023

medium

2187. Minimum Time to Complete Trips

Kotlin

Do a binary search. For the hi value, we can peak a $$10^7$$ or just compute all the time it takes for every bus to trip.

Binary Search Simulation

Full post LeetCode Kotlin Telegram

3.02.2023

medium

6. Zigzag Conversion

Kotlin

Store simulation result in a [rowsNum][simulation indice] - matrix, then build the result.

Simulation String Array

indices result zigzag_simulation modulo_based_direction row_by_index_tracking string_manipulation

Full post LeetCode Kotlin Telegram

8.11.2022

easy

Make The String Great

Kotlin

The simplest solution is just to simulate all the process, as input string is just 100 symbols.

Simulation String

char array (toCharArray) string manipulation nested loops for pairwise comparison iterative process to resolve conflicts checking adjacent/non-adjacent characters for equality and difference string processing

Full post LeetCode

Simulation

98 entries