Heaps
3 programs — patterns, complexity, and code
| # | Program Name | Pattern | Time | Space | Key Idea | Level |
|---|---|---|---|---|---|---|
| 1 | kthLargestElement | Min-Heap of size k | O(n log k) | O(k) | Keep a min-heap of size k; the root is always the kth largest seen so far. | Middle |
| 2 | topKFrequentElements | HashMap + Heap | O(n log k) | O(n) | Count frequencies, then use a min-heap of size k to retain top k elements. | Middle |
| 3 | mergeKSortedLists | Min-Heap | O(n log k) | O(k) | Push head of each list into min-heap; always extract minimum and push its next. | Complex |