🚀 LeetCode Daily Challenge Complete! Just solved "Find X-Sum of All K-Long Subarrays II" - Part II requires sophisticated two-set optimization! 💡 Solution Evolution: Naive Approach (TLE): ❌ Rebuild frequency map + heap for each window ❌ O(n × k × log k) - too slow for large inputs Optimized Two-Set Solution: ✅ Maintain two ordered sets: top (x elements) and bottom (rest) ✅ Track running sum of top set ✅ On element added: Update frequency, rebalance sets ✅ On element removed: Update frequency, rebalance from bottom ✅ O(n log n) - OPTIMAL! ✨ The key insight: Don't rebuild from scratch! Maintain top-x elements in an ordered set ordered by (frequency, value). When frequencies change, efficiently move elements between top and bottom sets. Running sum updates incrementally instead of recalculating! Critical operations: - Add: Insert to top, demote smallest if size > x - Remove: Delete from appropriate set, promote from bottom if needed - Both operations: O(log n) with set rebalancing Time: O(n×k×log k) → O(n log n) | Space: O(n) #LeetCode #HardProblems #CPlusPlus #Algorithms #SoftwareEngineering #ProblemSolving #TwoSetPattern #Optimization

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