C++ bitset array依數字 3、13、177、31622分割解Leetcode 3020 Find the Maximum Number of Elements in Subset
不用hashmap，另圖蹊徑才有辦法快速解答Leetcode 3020.
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No Hashmap—forging a new path to crush LeetCode 3020 fast.
Trick: isqrt(1e9)=31622 , 177, 13, 3
[codes on Leetcodes]https://leetcode.com/problems/find-the-maximum-number-of-elements-in-subset/solutions/8360422/divide-nums-according-to-3-1317731622bea-5tk4/
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English timestamps:
00:00 – Introduction and Problem Overview (LeetCode 3020)
00:26 – Performance Preview: 2ms Execution Time
01:00 – Understanding the Subset Pattern Requirements
01:46 – Constraints Analysis: Handling Large Numbers (up to $10^9$)
02:23 – Case Study: Valid vs. Invalid Subsets
04:59 – Strategy: Why Use Bitset Array instead of Hashmap?
05:52 – Optimization Logic: Square Root and Frequency Counting
07:45 – Implementing Bitset for Large Perfect Squares
09:14 – Code Walkthrough: Initialization and Reset Logic
11:00 – Special Case: Handling the Number 1
12:23 – Core Algorithm: Nested Loops and Early Stopping
14:38 – Detailed Logic for Perfect Squares in Bitset
16:16 – Updating the Maximum Length and Performance Optimization
17:02 – Final Code Refinement and Submission
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