C++| BFS hashmap linked list|Leetcode hard 1345 Jump Game 4| beats 100%
單純BFS+2D hash table就是慢點，至不多都是類似的解答，有什麼意思？把2D 器壓平成linked list才是王道。
在這部影片中，我們將挑戰 LeetCode 難度為 Hard 的第 1345 題：Jump Game IV。 雖然這是一道典型的 BFS 題目，但為了達到 Beats 100% 的極致效能，我們巧妙地結合了 Linked List 與 Hashmap 來優化節點的存取，有效加速計算。
內容涵蓋： ✅ 核心思路：如何將問題轉換為圖的遍歷 ✅ 優化關鍵：利用 Linked List 處理重複的數值節點 ✅ C++ 完整程式碼實作與解說
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A simple BFS + 2D hash table approach is slow, and at most, the solutions are similar. What's the point? The key is to flatten the 2D hash table into linked lists.
In this video, we tackle LeetCode 1345. Jump Game IV (Hard). While BFS is the standard approach, achieving 100% performance (Beats 100%) requires smart optimization. We demonstrate how to leverage a Linked List and Hashmap combination to efficiently manage node traversal and speed up.
What's inside: ✅ Step-by-step logic: Converting the problem into a graph traversal ✅ The Secret Sauce: Using Linked Lists for constant-time node removal ✅ Complete C++ implementation and walk-through
[codes on Leetcode]https://leetcode.com/problems/jump-game-iv/solutions/8258515/bfshashtable59ms-beats-9953-by-anwendeng-lpze/
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Here are the English timestamps and a structural breakdown for the video C++| BFS hashmap linked list|Leetcode hard 1345 Jump Game 4| beats 100%:
[00:01] Introduction and overview of LeetCode 1345: Jump Game IV (Hard).
[00:37] Problem description breakdown, explaining the jumping mechanics ($i+1$, $i-1$, and matching values).
[01:51] Walking through Example 1, Example 2, and Example 3.
[03:10] Analyzing problem constraints and determining the Breadth-First Search (BFS) approach.
[04:05] Explaining why std::unordered_map is needed to handle the element value constraints.
[04:45] Strategic comparison of two approaches: a standard 2D container vs. an optimized 1D hash table utilizing an array-based linked list.
[06:22] Code walkthrough for Approach 1 (Standard 2D container map implementation).
[08:57] Detailed explanation of the primary BFS level-order traversal loops for Approach 1.
[10:57] Performance discussion of Approach 1 (resulting in approximately 59ms runtime).
[11:10] Code walkthrough for Approach 2 (Optimizing performance with a 1D hash table and a nxt array for linked list headers).
[13:04] Deep dive into the optimized BFS loop utilizing the linked list structure.
[15:24] LeetCode platform submission, code execution, and result verification (34ms, beating 100% of C++ submissions).
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