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Problem

Merge K Sorted Lists

LeetCode #23Hard
Min-heap of the k current heads

Given an array of k linked lists, each sorted in ascending order, merge them into a single sorted linked list and return its head.

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step 1 / 79
list 0
list 1
list 2
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merged output
Brute force · scan k heads each round
▸
1given k sorted lists
2repeat until all empty:
3    scan the ≤ k current heads
4    move the minimum to output
5    advance that list
state
  • k lists3
  • total8

line 1Merge 3 sorted lists into one sorted list. The answer always starts with the smallest CURRENT head across the lists. Brute: each round, scan all 3 heads and take the min.