42 lines
1.1 KiB
Swift
42 lines
1.1 KiB
Swift
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/**
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* Definition for singly-linked list.
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* public class ListNode {
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* public var val: Int
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* public var next: ListNode?
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* public init() { self.val = 0; self.next = nil; }
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* public init(_ val: Int) { self.val = val; self.next = nil; }
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* public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
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* }
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*/
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class Solution {
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func mergeKLists(_ lists: [ListNode?]) -> ListNode? {
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var lists = lists.filter { $0 != nil }
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let root = ListNode()
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var node = root
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while !lists.isEmpty {
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// find the next list
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var minIdx = 0
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for i in 1..<lists.count {
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if lists[i]!.val < lists[minIdx]!.val {
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minIdx = i
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}
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}
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// insert the list into the node
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node.next = lists[minIdx]
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node = lists[minIdx]!
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// shift the list at the index or remove it
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if lists[minIdx]!.next == nil {
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lists.remove(at: minIdx)
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} else {
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lists[minIdx] = lists[minIdx]!.next
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}
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}
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return root.next
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}
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}
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