diff --git a/0528_swapping-nodes-in-a-linked-list/README.md b/0528_swapping-nodes-in-a-linked-list/README.md new file mode 100644 index 0000000..aa0bfde --- /dev/null +++ b/0528_swapping-nodes-in-a-linked-list/README.md @@ -0,0 +1,23 @@ +You are given the `head` of a linked list, and an integer `k`. + +Return _the head of the linked list after **swapping** the values of the_ `kth` _node from the beginning and the_ `kth` _node from the end (the list is **1-indexed**)._ + +**Example 1:** + +![](https://assets.leetcode.com/uploads/2020/09/21/linked1.jpg) + + Input: head = [1,2,3,4,5], k = 2 + Output: [1,4,3,2,5] + + +**Example 2:** + + Input: head = [7,9,6,6,7,8,3,0,9,5], k = 5 + Output: [7,9,6,6,8,7,3,0,9,5] + + +**Constraints:** + +* The number of nodes in the list is `n`. +* `1 <= k <= n <= 105` +* `0 <= Node.val <= 100` \ No newline at end of file diff --git a/0528_swapping-nodes-in-a-linked-list/python3/solution.py b/0528_swapping-nodes-in-a-linked-list/python3/solution.py new file mode 100644 index 0000000..e69de29 diff --git a/0528_swapping-nodes-in-a-linked-list/python3/using_dict.py b/0528_swapping-nodes-in-a-linked-list/python3/using_dict.py new file mode 100644 index 0000000..7e78925 --- /dev/null +++ b/0528_swapping-nodes-in-a-linked-list/python3/using_dict.py @@ -0,0 +1,17 @@ +# NOTE: Not the best approach, since we use O(N) space +# Time: O(N) +class Solution: + def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]: + # Figure out length of LL and cache nodes by the index + length = 0 + cache = {} + + ptr = head + while ptr != None: + cache[length] = ptr + length += 1 + ptr = ptr.next + + cache[k - 1].val, cache[length - k].val = cache[length - k].val, cache[k - 1].val + + return head