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LeetCode Hot 100 Overview

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This series focuses on LeetCode Hot 100.
The goal is not to dump 100 isolated solutions, but to help you:

  • Build a mental map of what each problem is really testing (data structures & patterns).
  • Design a learning path from easy to hard while covering each key topic.
  • Understand why a certain Java solution works, instead of memorizing templates.

Suggested order by topic

Instead of solving problems in numeric order, group them by topic:

  1. Basic data structures / stack / queue
    • Valid Parentheses (the first example in this series)
    • Min Stack, Implement Queue using Stacks, etc.
  2. Hash table & set
    • Two Sum, Longest Substring Without Repeating Characters, etc.
  3. Two pointers & sliding window
    • Container With Most Water, 3Sum, Sliding Window Maximum, etc.
  4. Linked list
    • Reverse Linked List, Linked List Cycle, Add Two Numbers, etc.
  5. Trees / binary trees
    • Binary Tree Level Order Traversal, Symmetric Tree, Maximum Depth of Binary Tree, etc.
  6. Backtracking & search
    • Permutations, Combination Sum, Subsets, etc.
  7. Dynamic programming
    • House Robber, Longest Increasing Subsequence, Edit Distance, etc.

Think of Hot 100 as a curated pool, and use topic-based blocks + difficulty ramps to get the most out of it.

How this documentation is structured

Under the small category “Algorithms / LeetCode hot100”:

  • This overview page:
    • Explains the overall roadmap and how problems are grouped.
    • Its summary is used for the “Algorithms” card on the docs home page.
  • Each individual problem page (e.g. 020 - Valid Parentheses):
    • Focuses on one problem: statement, key idea, and Java implementation.
    • When you open any problem, the left sidebar will list all problems under the same topic (LeetCode hot100), so you can navigate within the series.

So:

  • To see “how to approach the whole Hot 100 set” → read this overview.
  • To dive into a particular problem → use the sidebar under the LeetCode hot100 topic.

Mapping to the Chinese version

For bilingual readers, this series is maintained in both languages:

  • Chinese: section: "算法", topic: "LeetCode hot100".
  • English: section: "Algorithms", topic: "LeetCode hot100".

Switching between /zh/docs/ and /en/docs/ will keep the same overall structure, with explanations localized.