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Kotlin archive

Every library entry that currently exposes Kotlin code or a Kotlin solution link.

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1281 entries

Daily solutions with Kotlin available either directly in the archive or via linked solution pages.

04.01.2025

medium

1930. Unique Length-3 Palindromic Subsequences

Kotlin Rust

Count palindromes of length 3

building a HashSet can be slower then just checking for contains 26 times using unordered_set to count unique characters in the substring finding the span between first and last occurrences of a character counting unique characters within the substring defined by character occurrences manipulating and analyzing string content implicit use of string as an array of characters
Full post LeetCode Kotlin Rust YouTube Telegram

27.08.2024

medium

1514. Path with Maximum Probability

Kotlin Rust

Max path in a weighted graph

Graph
g queue shortest path calculation via probability multiplication using a priority queue (implicitly via BFS/queue structure) to find paths with maximum probability, updating probabilities based on multiplicative factors. building an adjacency list representation for the graph where edges store transition probabilities. weighted directed/undirected graph with probability weights
Full post LeetCode Kotlin Rust YouTube Telegram

14.10.2023

hard

2742. Painting the Walls

Kotlin

Min cost to complete all tasks using one paid cost[] & time[] and one free 0 & 1 workers

dp_memo depth-first-search memoization_with_state_compression bit-shifting_for_state_storage scheduling_and_cost_minimization implicit_state_space
Full post LeetCode Kotlin Telegram

25.05.2023

medium

837. New 21 Game

Kotlin

Probability sum of random numbers 1..maxPts sum be < n after it overflow k.

cache depth-first-search memoization_with_recurrence algebraic_manipulation boundary_condition_analysis probability
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

29.01.2023

hard

460. LFU Cache

Kotlin

one thing to note, on each increaseFreq operation we are retrieving a random item from TreeMap, that increases time to O(log(F)), where F is a unique set of frequencies.

TreeMap LinkedHashSet Frequency Bucketing Ordered Access Lists Cache Data Structures
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

1.11.2022

medium

Where Will The Ball Fall

Kotlin

This is a geometry problem, but seeing the pattern might help. We can spot that each row is an action sequence: -1 -1 -1 shifts balls left, and 1 1 1 shifts balls to the right. Corners can be formed only with -1 1 sequence.

Math Array
indToBall iterative_update tracking_ball_positions identifying_shift_rules grid_manipulation
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