# Dokicode

> Dokicode (https://dokicode.com) is a free Japanese visual novel (Bishoujo ADV / Galgame) and Chrome Extension companion for LeetCode practice. Players sign a study contract with one of 6 voiced heroines, practice over 2,000 rated LeetCode problems across a 12-plan algorithm route or 5 curated interview study plans (Blind 75, Grind 75, Grind 169, NeetCode 150, NeetCode 250), and receive 4-step progressive hints that guide problem-solving without spoiling solution code.

## Why Engineers Use Dokicode

- **Non-Spoiler 4-Step Progressive Hints**: Step 1 (Direction), Step 2 (Key Idea / Invariant), Step 3 (Approach Outline & Target Complexity), and Step 4 (Edge Cases & optional BYOK live AI coaching). Never dumps full editorial code prematurely.
- **Unified Study Plans & Shared Progress**: Includes both the 12-plan EndlessCheng (`lc-rating`) algorithm route (2,000+ problems with zerotrac contest ratings) and the 5 standard coding interview lists (Blind 75, Grind 75, Grind 169, NeetCode 150, NeetCode 250). Solving a problem once marks it solved across every plan.
- **Live LeetCode Chrome Extension (MV3)**: Accompanies you directly on `https://leetcode.com/problems/*`, reacts to every Run Code and Submit verdict in real time with Japanese voice lines, and syncs Accepted solves back to the study room without reading your source code.
- **Spaced Repetition & Study Room Atmosphere**: Schedules review problems after Accepted solves, features 6 voiced heroines (R0–R5 relationship stories), a 20-track lo-fi study music player, and study room backgrounds that shift with your local clock (morning, afternoon, evening, late night).
- **4 UI & Hint Locales**: Full interface, hint ladders, and story dialogue in English (`en`), Traditional Chinese (`zh-TW`), Simplified Chinese (`zh-CN`), and Japanese (`ja`), with Japanese character voice acting.

## Core Pages

- [Study Room Web App](https://dokicode.com/): Main interactive visual novel & LeetCode study room.
- [Full LLM Knowledge Base](https://dokicode.com/llms-full.txt): Complete single-file Markdown documentation of all heroines, study plans, features, release notes, and FAQs.
- [Chrome Extension Overview](https://dokicode.com/official/): How the Dokicode Chrome Extension works on leetcode.com.
- [Meet the Six Heroines](https://dokicode.com/heroines): Character profiles, occupations, algorithm specialties, and sample lines for Rin Ayase, Koharu Minami, Fuuka Hoshino, Yoru Kurokawa, Rei Kirisaki, and Karen Saionji.
- [Curriculum & Study Plans](https://dokicode.com/curriculum): Overview of the two-track 12-plan algorithm route and the 5 interview study plans.
- [Features & 4-Step Hints](https://dokicode.com/features): Detailed walkthrough of progressive hints, spaced review, rating ceilings, and the Chrome Extension.
- [Release Notes (What's New)](https://dokicode.com/releases): Full version history and changelog.
- [Frequently Asked Questions](https://dokicode.com/faq): Pricing (free), study plan selection guide, privacy, and browser support.
- [Privacy Policy](https://dokicode.com/privacy): Data handling and Chrome Extension privacy guarantees.

## Curated Coding Interview Study Plans

- [Blind 75 LeetCode Study Plan](https://dokicode.com/plans/blind-75): All 75 Blind 75 LeetCode problems organized across 18 algorithm topics, with difficulty levels, zerotrac contest ratings, and 4-step progressive hints in Dokicode.
- [Grind 75 LeetCode Study Plan](https://dokicode.com/plans/grind-75): All 75 Grind 75 LeetCode problems organized into a 5-week interview prep schedule by the author of Blind 75, with difficulty ratings and 4-step hints.
- [Grind 169 LeetCode Study Plan](https://dokicode.com/plans/grind-169): All 169 Grind 169 LeetCode problems across 11 weekly milestones, expanding Grind 75 with deeper graph, dynamic programming, binary search, and design problems.
- [NeetCode 150 LeetCode Study Plan](https://dokicode.com/plans/neetcode-150): All 150 NeetCode 150 LeetCode problems organized across 18 algorithm and data structure topics, with difficulty levels, zerotrac ratings, and 4-step hints.
- [NeetCode 250 LeetCode Study Plan](https://dokicode.com/plans/neetcode-250): All 250 NeetCode 250 LeetCode problems across 18 algorithm topics, adding gentler warm-ups and deeper follow-ups to NeetCode 150 with zerotrac ratings.

## 12-Plan LeetCode Algorithm Route (with zerotrac Contest Ratings)

- [Sliding Window & Two Pointers](https://dokicode.com/plans/sliding-window): 194 LeetCode sliding window and two pointer problems, ordered by chapter from fixed-length windows to grouped iteration, each tagged with its zerotrac rating.
- [Binary Search](https://dokicode.com/plans/binary-search): 103 LeetCode binary search problems ordered by chapter, from classic binary search to binary search on the answer and ternary search, with zerotrac ratings.
- [Monotonic Stack](https://dokicode.com/plans/monotonic-stack): 35 LeetCode monotonic stack problems ordered by chapter: next greater element, histogram rectangles, the contribution method and smallest lexicographical order.
- [Data Structures](https://dokicode.com/plans/data-structures): 366 LeetCode data structure problems in 13 chapters, from prefix sums and heaps to union-find and segment trees, ordered by chapter with zerotrac ratings.
- [Bit Manipulation](https://dokicode.com/plans/bit-manipulation): 95 LeetCode bit manipulation problems in nine chapters, from XOR, AND and OR properties to trial filling and linear basis, ordered with zerotrac ratings.
- [Greedy Algorithms](https://dokicode.com/plans/greedy): 254 LeetCode greedy problems ordered by chapter, from interval scheduling and string greedy to constructive and interactive problems, with zerotrac ratings.
- [Mathematics](https://dokicode.com/plans/math): 189 LeetCode math problems ordered by chapter: number theory, combinatorics, probability, game theory and computational geometry, each with its zerotrac rating.
- [Strings & Automata](https://dokicode.com/plans/strings): 31 LeetCode string algorithm problems ordered by chapter: KMP, Z-algorithm, Manacher, string hashing, Aho-Corasick and suffix arrays, with zerotrac ratings.
- [Linked Lists, Trees & Backtracking](https://dokicode.com/plans/trees-backtracking): 292 LeetCode problems on linked lists, binary trees, general trees, backtracking and divide and conquer, ordered by chapter with zerotrac contest ratings.
- [Grid & Matrix](https://dokicode.com/plans/grid): 47 LeetCode grid and matrix problems ordered by chapter, from grid DFS and BFS to 0-1 BFS and mixed applications, each with its zerotrac contest rating.
- [Dynamic Programming](https://dokicode.com/plans/dynamic-programming): 465 LeetCode dynamic programming problems in 20 chapters, from introductory DP and knapsack to interval, bitmask, digit and tree DP, with zerotrac ratings.
- [Graph Algorithms](https://dokicode.com/plans/graphs): 109 LeetCode graph problems ordered by chapter: traversal, topological sort, shortest paths, spanning trees and network flow, each with its zerotrac rating.

## Localized Editions

- [Traditional Chinese (繁體中文)](https://dokicode.com/zh-tw/): Complete site, curriculum, and 17 study plans in Traditional Chinese.
- [Simplified Chinese (简体中文)](https://dokicode.com/zh-cn/): Complete site, curriculum, and 17 study plans in Simplified Chinese.
- [Japanese (日本語)](https://dokicode.com/ja/): Complete site, curriculum, and 17 study plans in Japanese.