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# Runtime: 784 ms (Top 40.9%) | Memory: 50.79 MB (Top 42.2%)
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class Solution:
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    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
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        tot = 0  # initialise total
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        Head = head
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        while Head:  # count total nodes
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            Head = Head.next  # move forward
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            tot += 1  # incerse count by one for each node
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        one, two = None, None  # two pointers of one and two
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        count = (
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            1  # we're initialising to one because we have one based index for swapping
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        )
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        Head = head  # regain original head to traverse
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        while Head:
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            if one and two:
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                break  # if we have both one and two then break loop to save time
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            if (
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                count == k
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            ):  # if from forward we reach at node k then it's our first node
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                one = Head
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            if count == (
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                tot - k + 1
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            ):  # if from backward we reach to node k then save it
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                two = Head
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            Head = Head.next  # move further
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            count += 1  # increse count
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        one.val, two.val = two.val, one.val  # now swap values
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        return head  # return head