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From Code To Clarity. DHEETCODE.

An AST visual execution engine for LeetCode problem patterns and distributed system designs. Inspect variable scopes, stack frames, pointer convergence, and network packet flows in real-time.

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two_sum_trace.ts — Execution Frame 1/4

O(N) Time • O(N) Space

Live Replay

// Target: 9 | nums: [2, 7, 11, 15]

1function twoSum(nums: number[], target: number): number[] {

2 const map = new Map<number, number>();

3 for (let i = 0; i < nums.length; i++) {

4 const complement = target - nums[i];

5 if (map.has(complement)) return [map.get(complement)!, i];

6 map.set(nums[i], i);

7 }

8 return [];

9}

Scope VariablesStep 1 of 4

Pointer i

0

Value nums[i]

2

Complement

7

HashMap State (Key → Index)

Empty Map {}

Execution Action

Read nums[0] = 2. Complement = 9 - 2 = 7. map.has(7) is false.

Deterministic Step-Back Engine

State transitions are captured as immutable execution snapshots. Step backwards and forwards through any nested loop or recursion call-stack without losing state.

Zero JIT Inaccuracy • Pure AST Walk

Multi-Language AST Mapping

Toggle between TypeScript, C++, and Java on the fly. The visualizer maintains synchronized line highlights and variable models regardless of syntax dialect.

V8 • Clang • OpenJDK Semantics

Distributed Systems Sandbox

Move beyond algorithms. Inspect distributed caching, token bucket rate limiters, WebSocket routing, and queue buffering with live traffic and chaos engineering.

Real Topology • Failure Injection

Distributed Architectures

System Design Simulation Sandboxes

Interactive 2D architectural topologies with real-time SVG packet pulses, dynamic traffic generators, and chaos failure injection.

Explore all blueprints

Distributed URL Shortener

Base62 encoding, Redis Cache-Aside layer, PostgreSQL B-Tree unique indexing, and 301 vs 302 redirection analysis.

Writes: 193/sStorage: 15 TBP99: <15ms

Distributed Rate Limiter

Token Bucket & Sliding Window counter, atomic Redis Lua scripts, HTTP 429 throttling, and Fail-Open vs Fail-Closed policies.

Peak QPS: 35,000Eval: <1msRedis RAM: ~1 GB

Real-Time Chat Application

Bi-directional WebSockets, Redis Pub/Sub cross-server message routing, Cassandra wide-column partitions, and presence tracking.

Sockets: 10MDelivery: <50msTwitter Snowflake

Push Notification Service

RabbitMQ priority queues (OTP vs Marketing), idempotency deduplication keys, APNs/FCM delivery, and Dead Letter Queue (DLQ).

Throughput: 18,000/sDelivery SLA: 99.99%DLQ Quarantine

Algorithm Directory

152 Solved Algorithm Workspaces

Select an algorithm pattern to inspect step-by-step visualizers with custom inputs and multi-language AST execution.

Arrays & Hashing19 Problems

#firFirst Unique Character in a String

#conContains Duplicate

#valValid Anagram

#ranRansom Note

#maxMaximum Number of Balloons

#lonLongest Palindrome

#groGroup Anagrams

#topTop K Frequent Elements

#encEncode and Decode Strings

#proProduct of Array Except Self

#valValid Sudoku

#lonLongest Consecutive Sequence

#insInsert Interval

#merMerge Intervals

#nonNon-overlapping Intervals

#meeMeeting Rooms

#meeMeeting Rooms II

#minMinimum Interval to Include Each Query

Click any problem to launch interactive execution workspace.100% Free Access

Developer Tooling

DheetCode LeetCode Companion Extension

Dock the full execution visualizer directly into your LeetCode problem sidebar.

Download (.zip)

01 · Extract

Unzip dheetcode-companion.zip to a local folder.

02 · Developer Mode

Open chrome://extensions and enable Developer Mode.

03 · Load Unpacked

Click Load Unpacked, select folder, and solve on LeetCode!

Documentation

Frequently Asked Questions

Yes. All 152 DSA visualizers and all 4 distributed system design sandboxes are fully accessible without a paywall, account creation, or credit card.