Created
January 19, 2020 12:40
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24. Swap Nodes in Pairs
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| class Solution { | |
| func swapPairs(_ head: ListNode?) -> ListNode? { | |
| guard let newHead = head?.next else { | |
| return head | |
| } | |
| // 1 -> 2 -> 3 -> 4 | |
| // 2 -> 1 -> 4 -> 3 | |
| let tmp = head?.next?.next | |
| head?.next?.next = head | |
| head?.next = swapPairs(tmp) | |
| return newHead | |
| } | |
| } |
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