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Deven
19 lines
524 B
Python
19 lines
524 B
Python
# Definition for singly-linked list.
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# class ListNode:
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# def __init__(self, val=0, next=None):
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# self.val = val
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# self.next = next
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class Solution:
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def swapPairs(self, head: Optional[ListNode]) -> Optional[ListNode]:
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if head == None or head.next == None:
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return head
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first = head
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second = head.next
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first.next = second.next
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second.next = first
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first.next = self.swapPairs(first.next)
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return second |