K-way Merge — Heap (Priority Queue) Patterns
The K-way Merge pattern applies when you need the K-way Merge technique within the Heap (Priority Queue) Patterns pattern. Its time complexity is O(n log k) and space complexity O(k). It is used in 4 problems on Thita, including Find K Pairs with Smallest Sums, Kth Smallest Element in a Sorted Matrix and Merge k Sorted Lists. Common variations are Two Heaps for Median Finding and Top K Elements (Selection/Frequency).
Master K-way merge pattern using min heap. Merge k sorted lists and find kth smallest in matrix.
K-way Merge is one of the 4 subpatterns of the Heap (Priority Queue) Patterns pattern, which covers top K elements, K-way merge, two heaps for median, and scheduling. The whole pattern is about 2 hours of study. This subpattern is a core technique: expect it to come up directly in interviews.
What K-way Merge covers
Master heap-based algorithms including top K elements, two heaps for median, K-way merge, and scheduling problems with priority queues. Problems in this subpattern are usually searched for as k-way merge, merge k sorted lists, heap merge, kth smallest matrix, leetcode 23, leetcode 378.
How to practise K-way Merge on Thita.ai
Read the theory for K-way Merge, then work the problems attached to it in the browser editor. Your solution runs against the problem's test cases, and the AI coach offers a hint about the technique you are missing rather than a finished solution. Progress is tracked per subpattern, so the Heap (Priority Queue) Patterns tracker shows this one as covered once you have solved its problems.
Other subpatterns in Heap (Priority Queue) Patterns
- Top K Elements (Selection/Frequency) — Find top K elements using heap. Solve kth largest, top K frequent, and k closest points problems.
- Two Heaps for Median Finding — Master the two heaps technique to find median from data stream in O(log n) time.
- Scheduling / Minimum Cost (Greedy with Priority Queue) — Solve scheduling and optimization problems using priority queue with greedy approach.
Related DSA patterns
- String Manipulation Patterns — Palindrome checking, anagram detection, pattern matching, and string conversion.
- Tree Traversal Patterns (DFS & BFS) — Preorder, inorder, level order traversal, LCA, and serialization.
- Greedy Patterns — Interval scheduling, jump games, stock trading, and task scheduling.
- Backtracking Patterns — Subsets, permutations, combinations, N-Queens, and word search.
Where to go next
K-way Merge is one lesson in a 16-pattern DSA course. If you are preparing end to end, work the interview-critical patterns first and use the pattern sheet as the checklist; if you are here for one technique, the Heap (Priority Queue) Patterns guide is the shortest path back to the rest of it.